A special winding iron-core is designed to act as the snubber for the neutral beaminjection (NBI) power supply (PS) system in EAST, which will limit the fault current and energycaused by occasional sparking in the NBI...A special winding iron-core is designed to act as the snubber for the neutral beaminjection (NBI) power supply (PS) system in EAST, which will limit the fault current and energycaused by occasional sparking in the NBI ion source. 50-50 Ni-Fe is chosen as the high-frequencymagnetization material for the iron-core. Equations for the snubber is derived from the designof the iron-core. The iron-loss factor and eddy-current losses are found to increase in a sampleexperiment at a frequency from 1 kHz to 20 kHz. A 1:10 miniature of the iron-core is tested andperforms well with a fine capability.展开更多
A study of the magnetic field with an unsaturated iron core in tokamak equilibriumusing a spool model is described in detail. The application of this model to the J-TEXT tokamakshows that the calculated results are in...A study of the magnetic field with an unsaturated iron core in tokamak equilibriumusing a spool model is described in detail. The application of this model to the J-TEXT tokamakshows that the calculated results are in good agreement with those measured experimentally. Atpresent this scheme is used to give the plasma configuration during J-TEXT's operation.展开更多
The amount of literature on both melting and thermal conductivity of iron at Earth’s core conditions is overwhelming and the discrepancies are very large.There is a broad range of experimental techniques each of whic...The amount of literature on both melting and thermal conductivity of iron at Earth’s core conditions is overwhelming and the discrepancies are very large.There is a broad range of experimental techniques each of which is flawed to a certain degree,which may explain the discrepancy.In this report,we present new data using a different method for determining the phase behavior and resistivity of iron in the laser-heated diamond cell by measuring the electrical resistance of both solid and liquid iron wires.The experiment avoids some of the major flaws of previous experiments,the most important of which is the detection of the onset of melting.These measurements confirm a shallow melting curve found earlier and the resistivity data imply a trend towards low thermal conductivity in the liquid outer core.展开更多
The presence of light element(s)in the Earth’s core is necessary in order to explain the observed density and velocity discrepancy for the core(Anderson and Ahrens,1994).O,Si,S,C and H were suggested as potential can...The presence of light element(s)in the Earth’s core is necessary in order to explain the observed density and velocity discrepancy for the core(Anderson and Ahrens,1994).O,Si,S,C and H were suggested as potential candidates based on cosmochemical considerations(Stevenson,1981).High-pressure experiment results,in conjunction with theoretical and cosmochemical evidences,argued that it is difficult for any one of them to account for the core展开更多
A transformer type iron core snubber,as a protective device against the stray capacitanceduring the breakdown in EAST,is analyzed in detail.Three kinds of topology arepresented.Then with the analysis for equivalent ci...A transformer type iron core snubber,as a protective device against the stray capacitanceduring the breakdown in EAST,is analyzed in detail.Three kinds of topology arepresented.Then with the analysis for equivalent circuit,the ranges of three key parameters,i.e.,secondary side resistance,leakage inductance and snubber inductance,are determined.By consideringthe saturation of the magnetic material,a design principle is also presented.A nearly1:10 core snubber is tested.It is proved that a high permeability core with secondary resistor canrestrain the discharge current effectively.展开更多
In a simple ethanol-water system,the magnetic α-Fe nanoparticles(with an average diameter of 10-40 nm)were prepared by reduction of Fe2 +using potassium borohydride in the presence of surfactant.Then the shell was fo...In a simple ethanol-water system,the magnetic α-Fe nanoparticles(with an average diameter of 10-40 nm)were prepared by reduction of Fe2 +using potassium borohydride in the presence of surfactant.Then the shell was formed by hydrolysis-condensation polymerization of tetraethylorthosilicate(TEOS)on the surface of the Fe particles.The samples were characterized by XRD,TEM,SAED,TG-DSC and VSM.The results indicate that a thin film of silica is coated on the surface of Fe particles through a Si-O-Fe bond.The coated shell of silica can effectively protect the Fe cores from being oxidized.展开更多
The formation mechanism of the spheroidal carbide in the ultra-low carbon ductile cast iron fabricated by the metal mold casting technique was systematically investigated. The results demonstrated that the spheroidal ...The formation mechanism of the spheroidal carbide in the ultra-low carbon ductile cast iron fabricated by the metal mold casting technique was systematically investigated. The results demonstrated that the spheroidal carbide belonged to eutectic carbide and crystallized in the isolated eutectic liquid phase area. The formation process of the spheroidal carbide was related to the contact and the intersection between the primary dendrite and the secondary dendrite of austenite. The oxides of magnesium, rare earths and other elements can act as heterogeneous nucleation sites for the spheroidal carbide. It was also found that the amount of the spheroidal carbide would increase with an increase in carbon content. The cooling rate has an important influence on the spheroidal carbide under the same chemical composition condition.展开更多
文摘A special winding iron-core is designed to act as the snubber for the neutral beaminjection (NBI) power supply (PS) system in EAST, which will limit the fault current and energycaused by occasional sparking in the NBI ion source. 50-50 Ni-Fe is chosen as the high-frequencymagnetization material for the iron-core. Equations for the snubber is derived from the designof the iron-core. The iron-loss factor and eddy-current losses are found to increase in a sampleexperiment at a frequency from 1 kHz to 20 kHz. A 1:10 miniature of the iron-core is tested andperforms well with a fine capability.
基金supported by National Basic Research Program ('973'Program)of China (No.2008CB717805)
文摘A study of the magnetic field with an unsaturated iron core in tokamak equilibriumusing a spool model is described in detail. The application of this model to the J-TEXT tokamakshows that the calculated results are in good agreement with those measured experimentally. Atpresent this scheme is used to give the plasma configuration during J-TEXT's operation.
基金supported by the National Science Foundation (No. 1248553)
文摘The amount of literature on both melting and thermal conductivity of iron at Earth’s core conditions is overwhelming and the discrepancies are very large.There is a broad range of experimental techniques each of which is flawed to a certain degree,which may explain the discrepancy.In this report,we present new data using a different method for determining the phase behavior and resistivity of iron in the laser-heated diamond cell by measuring the electrical resistance of both solid and liquid iron wires.The experiment avoids some of the major flaws of previous experiments,the most important of which is the detection of the onset of melting.These measurements confirm a shallow melting curve found earlier and the resistivity data imply a trend towards low thermal conductivity in the liquid outer core.
文摘The presence of light element(s)in the Earth’s core is necessary in order to explain the observed density and velocity discrepancy for the core(Anderson and Ahrens,1994).O,Si,S,C and H were suggested as potential candidates based on cosmochemical considerations(Stevenson,1981).High-pressure experiment results,in conjunction with theoretical and cosmochemical evidences,argued that it is difficult for any one of them to account for the core
基金supported in part by Auxiliary Heating Project of EAST upgradein part by Ph. D foundation of State Education Ministry of China(No. 20060248012)
文摘A transformer type iron core snubber,as a protective device against the stray capacitanceduring the breakdown in EAST,is analyzed in detail.Three kinds of topology arepresented.Then with the analysis for equivalent circuit,the ranges of three key parameters,i.e.,secondary side resistance,leakage inductance and snubber inductance,are determined.By consideringthe saturation of the magnetic material,a design principle is also presented.A nearly1:10 core snubber is tested.It is proved that a high permeability core with secondary resistor canrestrain the discharge current effectively.
文摘In a simple ethanol-water system,the magnetic α-Fe nanoparticles(with an average diameter of 10-40 nm)were prepared by reduction of Fe2 +using potassium borohydride in the presence of surfactant.Then the shell was formed by hydrolysis-condensation polymerization of tetraethylorthosilicate(TEOS)on the surface of the Fe particles.The samples were characterized by XRD,TEM,SAED,TG-DSC and VSM.The results indicate that a thin film of silica is coated on the surface of Fe particles through a Si-O-Fe bond.The coated shell of silica can effectively protect the Fe cores from being oxidized.
基金financially supported by the Hebei Province Science and Technology Support Program(No.14211007D)
文摘The formation mechanism of the spheroidal carbide in the ultra-low carbon ductile cast iron fabricated by the metal mold casting technique was systematically investigated. The results demonstrated that the spheroidal carbide belonged to eutectic carbide and crystallized in the isolated eutectic liquid phase area. The formation process of the spheroidal carbide was related to the contact and the intersection between the primary dendrite and the secondary dendrite of austenite. The oxides of magnesium, rare earths and other elements can act as heterogeneous nucleation sites for the spheroidal carbide. It was also found that the amount of the spheroidal carbide would increase with an increase in carbon content. The cooling rate has an important influence on the spheroidal carbide under the same chemical composition condition.