To investigate the radiative divertor behavior and physics for the scenario of impurity seeded plasma in ITER, the radiative divertor experiments with argon（Ar） seeding under ITER-like tungsten divertor condition we...To investigate the radiative divertor behavior and physics for the scenario of impurity seeded plasma in ITER, the radiative divertor experiments with argon（Ar） seeding under ITER-like tungsten divertor condition were carried out during recent EAST campaigns. The experimental results reveal the high efficiency of reducing heat load and particle flux onto the divertor targets owing to increased radiation by Ar seeding. We achieve detached plasmas in these experiments. The inner–outer divertor asymmetry reduces after Ar seeding. Impurities, such as Ar, C, Li, and W, exist in the entire space of the vacuum chamber during EAST operations, and play important roles in power exhausting and accelerating the plasma detachment process. It is remarkable that the contamination of the core plasma is observed using Ar seeding owing to the sputtering of plasma facing components（PFCs）, particularly when Ar impurity is injected from the upper tungsten divertor.展开更多
Tungsten is a promising candidate for plasma-facing materials to cover the surface of the divertor plate in the design of an international thermonuclear experimental reactor （ITER）. Copper as a heat sink material se...Tungsten is a promising candidate for plasma-facing materials to cover the surface of the divertor plate in the design of an international thermonuclear experimental reactor （ITER）. Copper as a heat sink material serves to transfer heat excellently. Divertor mock-ups with W/Cu graded interlayers were designed to reduce thermal stresses. Thermally induced stresses and temperature in a W/Cu divertor mock-up were analyzed using the finite element method. The graded structures with different exponents p and thick- nesses were designed and discussed. The conclusions drawn from these analyses are that thermal stresses reach the minimum and the temperature is suitable when exponent p is 1.5 and the thickness of five graded interlayers is 5 mm.展开更多
The influence of the J×B force on the topographical modification of W targets during a type-I-like ELM in ITER has been studied numerically. A two-dimensional(2D) fluid dynamics model is employed by solving liqui...The influence of the J×B force on the topographical modification of W targets during a type-I-like ELM in ITER has been studied numerically. A two-dimensional(2D) fluid dynamics model is employed by solving liquid hydrodynamic Navier-Stokes equation with the 2D heat conduction equation in addition to driving forces for surface topography, such as surface tension and pressure gradient, the J×B force is particularly addressed. The governing equations are solved with the finite volume method by adequate prediction of the moving solid-liquid interface. Numerical simulations are carried out for a range of type-I ELM characteristic parameters. Our results indicate that both the surface tension and the J×B force contributes to the melt motion of tungsten plates when the energy flux is under 3000 MW·m^(-2), the surface tension is a major driving force while the pressure gradient is negligible. Our results also indicate that the J×B force makes the small hills grow at different rates at both the crater edges under a type-I-like ELM heat load with a Gaussian power density profile.展开更多
The tungsten(W)material as the divertor of fusion reactors is exposed to low-energy and high-flux He/H isotope irradiation,leading to the growth of fuzz layers.The W fuzz growth does not show any dependence on the pla...The tungsten(W)material as the divertor of fusion reactors is exposed to low-energy and high-flux He/H isotope irradiation,leading to the growth of fuzz layers.The W fuzz growth does not show any dependence on the plasma irradiation devices used;however,it is strongly dependent on He^(+)fluence and energy,irradiation temperature,and impurity level.When the incident He ions collide inside the dense fuzz layers with the extremely high specific area,their mean free path can be up to 690 nm.Up to now,the He bubble-driven W fuzz growth process is not entirely understood;however,it can be closely related to the surface bursting of He bubbles in the W surface layer and W surface erosion by He^(+)implantation.The formation of He bubbles can be attributed to the solute He diffusion into defects or bubbles,which is strongly affected by the temperature and He^(+)fluence.The W fuzz grows over the W surface,where the micro-stress caused by He bubbles in the W surface layer acts as the driving force.The W fuzz layer inhibits He^(+)implantation into W bulk,and provides an entire protection against the He^(+)erosion into W bulk beneath the fuzz layer.In this review article,the current status of experiment and theory are presented,and some of the remaining issues are discussed.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11575242,11575243,11505233,11575247,and 11605238)the National Magnetic Confinement Fusion Science Program(Grant Nos.2013GB105002 and 2013GB105001)
文摘To investigate the radiative divertor behavior and physics for the scenario of impurity seeded plasma in ITER, the radiative divertor experiments with argon（Ar） seeding under ITER-like tungsten divertor condition were carried out during recent EAST campaigns. The experimental results reveal the high efficiency of reducing heat load and particle flux onto the divertor targets owing to increased radiation by Ar seeding. We achieve detached plasmas in these experiments. The inner–outer divertor asymmetry reduces after Ar seeding. Impurities, such as Ar, C, Li, and W, exist in the entire space of the vacuum chamber during EAST operations, and play important roles in power exhausting and accelerating the plasma detachment process. It is remarkable that the contamination of the core plasma is observed using Ar seeding owing to the sputtering of plasma facing components（PFCs）, particularly when Ar impurity is injected from the upper tungsten divertor.
基金This work was financially supported by the National High-Tech Research and Development Program of China ("863" Program)(No.2003AA305340)
文摘Tungsten is a promising candidate for plasma-facing materials to cover the surface of the divertor plate in the design of an international thermonuclear experimental reactor （ITER）. Copper as a heat sink material serves to transfer heat excellently. Divertor mock-ups with W/Cu graded interlayers were designed to reduce thermal stresses. Thermally induced stresses and temperature in a W/Cu divertor mock-up were analyzed using the finite element method. The graded structures with different exponents p and thick- nesses were designed and discussed. The conclusions drawn from these analyses are that thermal stresses reach the minimum and the temperature is suitable when exponent p is 1.5 and the thickness of five graded interlayers is 5 mm.
基金Project supported by the Scientific Research Foundation of Liaoning Province,China(Grant No.2016J027)the Open Research Project of Key Laboratory of Materials Modification by Laser,Ion and Electron Beams,Ministry of Education(Grant No.KF1705)the National Key Research and Development Program of China(Grant Nos.2017YFA0402500,2017YFE0300400,and 2017YFE0301200)
文摘The influence of the J×B force on the topographical modification of W targets during a type-I-like ELM in ITER has been studied numerically. A two-dimensional(2D) fluid dynamics model is employed by solving liquid hydrodynamic Navier-Stokes equation with the 2D heat conduction equation in addition to driving forces for surface topography, such as surface tension and pressure gradient, the J×B force is particularly addressed. The governing equations are solved with the finite volume method by adequate prediction of the moving solid-liquid interface. Numerical simulations are carried out for a range of type-I ELM characteristic parameters. Our results indicate that both the surface tension and the J×B force contributes to the melt motion of tungsten plates when the energy flux is under 3000 MW·m^(-2), the surface tension is a major driving force while the pressure gradient is negligible. Our results also indicate that the J×B force makes the small hills grow at different rates at both the crater edges under a type-I-like ELM heat load with a Gaussian power density profile.
基金supported by the National Key R&D Program of China(Grant No.2017YFE0300106)the National Science Foundation of China(Grant No.11320101005)+1 种基金Liaoning Provincial Natural Science Foundation(Grant Nos.20180510006 and 2019-ZD-0186)Dalian Science and Technology Star Project(Grant No.2017RQ149).
文摘The tungsten(W)material as the divertor of fusion reactors is exposed to low-energy and high-flux He/H isotope irradiation,leading to the growth of fuzz layers.The W fuzz growth does not show any dependence on the plasma irradiation devices used;however,it is strongly dependent on He^(+)fluence and energy,irradiation temperature,and impurity level.When the incident He ions collide inside the dense fuzz layers with the extremely high specific area,their mean free path can be up to 690 nm.Up to now,the He bubble-driven W fuzz growth process is not entirely understood;however,it can be closely related to the surface bursting of He bubbles in the W surface layer and W surface erosion by He^(+)implantation.The formation of He bubbles can be attributed to the solute He diffusion into defects or bubbles,which is strongly affected by the temperature and He^(+)fluence.The W fuzz grows over the W surface,where the micro-stress caused by He bubbles in the W surface layer acts as the driving force.The W fuzz layer inhibits He^(+)implantation into W bulk,and provides an entire protection against the He^(+)erosion into W bulk beneath the fuzz layer.In this review article,the current status of experiment and theory are presented,and some of the remaining issues are discussed.
