This paper summarizes recent achievements in the characterization ofcandidate vanadium alloys obtained for fusion in the framework of the Japan-China Core UniversityProgram. National Institute for Fusion Science (NIFS...This paper summarizes recent achievements in the characterization ofcandidate vanadium alloys obtained for fusion in the framework of the Japan-China Core UniversityProgram. National Institute for Fusion Science (NIFS) has a program of fabricating high-purityV-4Cr-4Ti alloys. The resulting products (NIFS-HEAT-1,2), were characterized by various researchgroups in the world including Chinese partners. South Western Institute of Physics (SWIP) fabricateda new V-4Cr-4Ti alloy (SWIP-Heat), and carried out a comparative evaluation of hydrogenembrittlement of NIFS-HEATs and SWIP-Heat. The tensile test of hydrogen-doped alloys showed that theNIFS-HEAT maintained the ductility to relatively high hydrogen levels. The comparison of the datawith those of previous studies suggested that the reduced oxygen level in the NIFS-HEATs should beresponsible for the increased resistance to hydrogen embrittlement. Based on the chemical analysisdata of NIFS-HEATs and SWIP-Heats, neutron-induced activation was analyzed in Institute of PlasmaPhysics (IPP-CAS) as a function of cooling time after the use in the fusion first wall. The resultsshowed that the low level of Co dominates the activity up to 50 years followed by a domination of Nbor Nb and Al in the respective alloys. It was suggested that reduction of Co and Nb, both of whichare thought to have been introduced via cross-contamination into the alloys from the molds usedshould be crucial for reducing further the activation.展开更多
Stationary electrostatic-potential formation in plasma with immovable dustparticles was investigated by using one-dimensional kinetic analysis. It is clarified that thedensity of negatively charged dust particles belo...Stationary electrostatic-potential formation in plasma with immovable dustparticles was investigated by using one-dimensional kinetic analysis. It is clarified that thedensity of negatively charged dust particles below the threshold value makes the potential decreasemonoton-ically. When the dust densities are above the threshold, there appears the stationaryoscillation in an electrostatic potential due to the streaming plasma. It is found that thewavelength of this mode is of the order of Debye length. These phenomena are different from those ofthe conventional dust ion-acoustic waves in plasma, where the effect of dust-charging is not takeninto account.展开更多
Recent observations on tokamaks have shown that, within internal transport barriers (ITBs), electron thermal transport hardly changes while ion thermal diffusivity is reduced to the neoclassical level. These findings ...Recent observations on tokamaks have shown that, within internal transport barriers (ITBs), electron thermal transport hardly changes while ion thermal diffusivity is reduced to the neoclassical level. These findings support the hypothesis that, within展开更多
Vanadium alloys, especially that of V4Cr4Ti, are supposed as the promising candidate structural material for fusion applications for their good thermal properties, high temperature strength and the inherent low activa...Vanadium alloys, especially that of V4Cr4Ti, are supposed as the promising candidate structural material for fusion applications for their good thermal properties, high temperature strength and the inherent low activation characteristics. However, in展开更多
In the previous models for the ion temperature(ITG)driven instability,the safety factor (r) is introduced into the model through the wavenumber or relative derivative,such sa kθ=lq(r)/r and △1=ik1=(Rq)^-1э/эθ.sin...In the previous models for the ion temperature(ITG)driven instability,the safety factor (r) is introduced into the model through the wavenumber or relative derivative,such sa kθ=lq(r)/r and △1=ik1=(Rq)^-1э/эθ.since the safety展开更多
High Z and low Z materials are both the candidate plasma facing materials (PFM), up to now, the typical representative of high Z materials is tungsten, and the representatives of low Z materials are carbon materials (...High Z and low Z materials are both the candidate plasma facing materials (PFM), up to now, the typical representative of high Z materials is tungsten, and the representatives of low Z materials are carbon materials (such as graphite, C/C composite) and beryllium. Most of these materials have been used as PFM limiters and diverter armor tiles of tokamak machines, tungsten, molybdenum and C/C composite are always used as high heat flux components.展开更多
基金The project supported by The Core-University Program on Plasma and Nuclear Fusion sponsored by JSPS(Japan)and CAS (China)
文摘This paper summarizes recent achievements in the characterization ofcandidate vanadium alloys obtained for fusion in the framework of the Japan-China Core UniversityProgram. National Institute for Fusion Science (NIFS) has a program of fabricating high-purityV-4Cr-4Ti alloys. The resulting products (NIFS-HEAT-1,2), were characterized by various researchgroups in the world including Chinese partners. South Western Institute of Physics (SWIP) fabricateda new V-4Cr-4Ti alloy (SWIP-Heat), and carried out a comparative evaluation of hydrogenembrittlement of NIFS-HEATs and SWIP-Heat. The tensile test of hydrogen-doped alloys showed that theNIFS-HEAT maintained the ductility to relatively high hydrogen levels. The comparison of the datawith those of previous studies suggested that the reduced oxygen level in the NIFS-HEATs should beresponsible for the increased resistance to hydrogen embrittlement. Based on the chemical analysisdata of NIFS-HEATs and SWIP-Heats, neutron-induced activation was analyzed in Institute of PlasmaPhysics (IPP-CAS) as a function of cooling time after the use in the fusion first wall. The resultsshowed that the low level of Co dominates the activity up to 50 years followed by a domination of Nbor Nb and Al in the respective alloys. It was suggested that reduction of Co and Nb, both of whichare thought to have been introduced via cross-contamination into the alloys from the molds usedshould be crucial for reducing further the activation.
文摘Stationary electrostatic-potential formation in plasma with immovable dustparticles was investigated by using one-dimensional kinetic analysis. It is clarified that thedensity of negatively charged dust particles below the threshold value makes the potential decreasemonoton-ically. When the dust densities are above the threshold, there appears the stationaryoscillation in an electrostatic potential due to the streaming plasma. It is found that thewavelength of this mode is of the order of Debye length. These phenomena are different from those ofthe conventional dust ion-acoustic waves in plasma, where the effect of dust-charging is not takeninto account.
文摘Recent observations on tokamaks have shown that, within internal transport barriers (ITBs), electron thermal transport hardly changes while ion thermal diffusivity is reduced to the neoclassical level. These findings support the hypothesis that, within
文摘Vanadium alloys, especially that of V4Cr4Ti, are supposed as the promising candidate structural material for fusion applications for their good thermal properties, high temperature strength and the inherent low activation characteristics. However, in
文摘In the previous models for the ion temperature(ITG)driven instability,the safety factor (r) is introduced into the model through the wavenumber or relative derivative,such sa kθ=lq(r)/r and △1=ik1=(Rq)^-1э/эθ.since the safety
文摘High Z and low Z materials are both the candidate plasma facing materials (PFM), up to now, the typical representative of high Z materials is tungsten, and the representatives of low Z materials are carbon materials (such as graphite, C/C composite) and beryllium. Most of these materials have been used as PFM limiters and diverter armor tiles of tokamak machines, tungsten, molybdenum and C/C composite are always used as high heat flux components.
