The investigation of dust particle characteristics in fusion devices has become more and more imperative.In the HL-2A tokamak,the morphologies and compositions of dust particles are analyzed by using scanning electron...The investigation of dust particle characteristics in fusion devices has become more and more imperative.In the HL-2A tokamak,the morphologies and compositions of dust particles are analyzed by using scanning electron microscopy（SEM） and energy dispersive x-ray spectroscopy（EDX） with mapping.The results indicate that the sizes of dust particles are in a range from 1 μm to 1 mm.Surprisingly,stainless steel spheres with a diameter of 2.5μm-30 μm are obtained.The production mechanisms of dust particles include flaking,disintegration,agglomeration,and arcing.In addition,dynamic characteristics of the flaking dust particles are observed by a CMOS fast framing camera and simulated by a computer program.Both of the results display that the ion friction force is dominant in the toroidal direction,while the centrifugal force is crucial in the radial direction.Therefore,the visible dust particles are accelerated toriodally by the ion friction force and migrated radially by the centrifugal force.The averaged velocity of the grain is on the order of^100 m/s.These results provide an additional supplement for one of critical plasma-wall interaction（PWI） issues in the framework of the International Thermonuclear Experimental Reactor（ITER） programme.展开更多
基金supported by the National Magnetic Confinement Fusion Science Program of China(Grant Nos.2014GB107000 and 2013GB112008)the National Natural Science Foundation of China(Grant Nos.11320101005,11175060,11375054,and 11075046)the China-Korean Joint Foundation(Grant No.2012DFG02230)
文摘The investigation of dust particle characteristics in fusion devices has become more and more imperative.In the HL-2A tokamak,the morphologies and compositions of dust particles are analyzed by using scanning electron microscopy（SEM） and energy dispersive x-ray spectroscopy（EDX） with mapping.The results indicate that the sizes of dust particles are in a range from 1 μm to 1 mm.Surprisingly,stainless steel spheres with a diameter of 2.5μm-30 μm are obtained.The production mechanisms of dust particles include flaking,disintegration,agglomeration,and arcing.In addition,dynamic characteristics of the flaking dust particles are observed by a CMOS fast framing camera and simulated by a computer program.Both of the results display that the ion friction force is dominant in the toroidal direction,while the centrifugal force is crucial in the radial direction.Therefore,the visible dust particles are accelerated toriodally by the ion friction force and migrated radially by the centrifugal force.The averaged velocity of the grain is on the order of^100 m/s.These results provide an additional supplement for one of critical plasma-wall interaction（PWI） issues in the framework of the International Thermonuclear Experimental Reactor（ITER） programme.
