The motion of current filaments in avalanching PIN diodes has been investigated in this paper by 2D transient numerical simulations. The simulation results show that the filament can move along the length of the PIN d...The motion of current filaments in avalanching PIN diodes has been investigated in this paper by 2D transient numerical simulations. The simulation results show that the filament can move along the length of the PIN diode back and forth when the self-heating effect is considered. The voltage waveform varies periodically due to the motion of the filament. The filament motion is driven by the temperature gradient in the filament due to the negative temperature dependence of the impact ionization rates. Contrary to the traditional understanding that current filamentation is a potential cause of thermal destruction, it is shown in this paper that the thermally-driven motion of current filaments leads to the homogenization of temperature in the diode and is expected to have a positive influence on the failure threshold of the PIN diode.展开更多
A magnetic measurement system consisting of magnetic probes and flux loops for spherical tokamak SUNIST, is uniquely designed due to the strongly shaped plasma cross section and the narrow space near the central solen...A magnetic measurement system consisting of magnetic probes and flux loops for spherical tokamak SUNIST, is uniquely designed due to the strongly shaped plasma cross section and the narrow space near the central solenoid. Plasma equilibrium reconstruction with the current filament method is performed to determine the number and positions of the magnetic probes and flux loops, as well as their design precision required.展开更多
In this paper, the bipolar resistive switching characteristic is reported in Ti/ZrO2/Pt resistive switching memory de- vices. The dominant mechanism of resistive switching is the formation and rupture of the conductiv...In this paper, the bipolar resistive switching characteristic is reported in Ti/ZrO2/Pt resistive switching memory de- vices. The dominant mechanism of resistive switching is the formation and rupture of the conductive filament composed of oxygen vacancies. The conduction mechanisms for low and high resistance states are dominated by the ohmic conduc- tion and the trap-controlled space charge limited current （SCLC） mechanism, respectively. The effect of a set compliance current on the switching parameters is also studied： the low resistance and reset current are linearly dependent on the set compliance current in the log-log scale coordinate; and the set and reset voltage increase slightly with the increase of the set compliance current. A series circuit model is proposed to explain the effect of the set compliance current on the resistive switching behaviors.展开更多
A method for the reconstruction of the plasma boundary in the sino-united spherical tokamak （SUNIST） based on the outer plasma magnetic diagnostics is reported. In SUNIST, the magnetic flux loop integral signals wer...A method for the reconstruction of the plasma boundary in the sino-united spherical tokamak （SUNIST） based on the outer plasma magnetic diagnostics is reported. In SUNIST, the magnetic flux loop integral signals were measured recently and the plasma boundary could be reconstructed well with a current filament （CF） model by setting 2 to 8 current filaments. There are three additional filament positional parameters in addition to the filament current to minimize the square root error in the CF model. The plasma configuration obtained with the CF method is consistent with the visible plasma image from the CCD camera. The average difference in the minor radii for the plasma boundary, by applying the CF model and EFIT code, is below 6 mm.展开更多
基金Project supported by the National Natural Science Foundation of China(No.60776034)
文摘The motion of current filaments in avalanching PIN diodes has been investigated in this paper by 2D transient numerical simulations. The simulation results show that the filament can move along the length of the PIN diode back and forth when the self-heating effect is considered. The voltage waveform varies periodically due to the motion of the filament. The filament motion is driven by the temperature gradient in the filament due to the negative temperature dependence of the impact ionization rates. Contrary to the traditional understanding that current filamentation is a potential cause of thermal destruction, it is shown in this paper that the thermally-driven motion of current filaments leads to the homogenization of temperature in the diode and is expected to have a positive influence on the failure threshold of the PIN diode.
基金National Science Foundation of China(No.10535020)the Foundation for the Authors of National Excellent Doctoral Dissertation of China(No.200456)
文摘A magnetic measurement system consisting of magnetic probes and flux loops for spherical tokamak SUNIST, is uniquely designed due to the strongly shaped plasma cross section and the narrow space near the central solenoid. Plasma equilibrium reconstruction with the current filament method is performed to determine the number and positions of the magnetic probes and flux loops, as well as their design precision required.
基金supported by the National Basic Research Program of China(Grant No.2011CBA00606)the National Natural Science Foundation of China(Grant Nos.61106106,11304237,61376099,and 11235008)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant Nos.20130203130002 and 20110203110012)
文摘In this paper, the bipolar resistive switching characteristic is reported in Ti/ZrO2/Pt resistive switching memory de- vices. The dominant mechanism of resistive switching is the formation and rupture of the conductive filament composed of oxygen vacancies. The conduction mechanisms for low and high resistance states are dominated by the ohmic conduc- tion and the trap-controlled space charge limited current （SCLC） mechanism, respectively. The effect of a set compliance current on the switching parameters is also studied： the low resistance and reset current are linearly dependent on the set compliance current in the log-log scale coordinate; and the set and reset voltage increase slightly with the increase of the set compliance current. A series circuit model is proposed to explain the effect of the set compliance current on the resistive switching behaviors.
基金supported by National Natural Science Foundation of China (Nos.10775177, 10535020)the Major State Basic Research Development Program of China (Program 973) (No.2008CB717804)
文摘A method for the reconstruction of the plasma boundary in the sino-united spherical tokamak （SUNIST） based on the outer plasma magnetic diagnostics is reported. In SUNIST, the magnetic flux loop integral signals were measured recently and the plasma boundary could be reconstructed well with a current filament （CF） model by setting 2 to 8 current filaments. There are three additional filament positional parameters in addition to the filament current to minimize the square root error in the CF model. The plasma configuration obtained with the CF method is consistent with the visible plasma image from the CCD camera. The average difference in the minor radii for the plasma boundary, by applying the CF model and EFIT code, is below 6 mm.
