Growth and passivation of tunnels within Al foil by on-off controlling DC etching in 6 wt.% HCI solution has been investigated. It was found that, in a given etchant solution at a special temperature, the longest tunn...Growth and passivation of tunnels within Al foil by on-off controlling DC etching in 6 wt.% HCI solution has been investigated. It was found that, in a given etchant solution at a special temperature, the longest tunnel length was only a function of the turn-on interval of DC. The potential of Al foil broke at on-off controlling DC by the result from anode polarization curves and potential-time （E-t） responding curves. When DC was switched on, the potential increased abruptly over pitting potential, leading to nucleation of pits at the surface and the growth of tunnels at special length. When DC was switched off, the potential decreased rapidly to a passive value, leading to stoppage of nucleation and death of tunnels. By this way, the longest tunnel length can be controlled and a non-piercing layer can be obtained. Hence, etching of Al foil at this current is beneficial for maintaining a good mechanical strength.展开更多
The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied, A computer code for solving the Fokker-Planck equation in a toroidal geometry is developed and employed. The co...The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied, A computer code for solving the Fokker-Planck equation in a toroidal geometry is developed and employed. The code is suitable for various auxiliary heating and current drive schemes in tokamak plasmas. The influence of the resonance regime on the current drive efficiency as well as the influence of trapped particle fraction on the current drive efficiency are emphasized. It is shown that, as an electrostatic force, the lower hybrid wave causes some of the trapped electrons to be untrapped and lose their energy, which can cut the LHCD efficiency by about 30%. The ITER scaling law is also used to estimate the trapped electron effects.展开更多
低杂波电流驱动(Lower Hybrid Current Drive,LHCD)是托卡马克的主要辅助加热与电流驱动方式之一,研究表明,低杂波在刮削层内的边界寄生效应会显著降低低杂波电流驱动效率。其中,边界密度涨落引起的波散射会导致刮削层内的低杂波波谱变...低杂波电流驱动(Lower Hybrid Current Drive,LHCD)是托卡马克的主要辅助加热与电流驱动方式之一,研究表明,低杂波在刮削层内的边界寄生效应会显著降低低杂波电流驱动效率。其中,边界密度涨落引起的波散射会导致刮削层内的低杂波波谱变化,从而改变低杂波功率沉积位置和电流驱动效率。本文使用全波解方法研究全超导托卡马克(Experimental Advanced Superconducting Tokamak,EAST)装置上刮削层内密度涨落导致的低杂波波散射,重点分析不同特征的低频电子密度涨落对波散射的影响。模拟结果表明:密度波包(blob)引起的散射导致低杂波功率流的空间结构的改变,blob造成的背向散射比前向散射更明显;blob内的密度涨落大小主要影响波场扰动幅度,blob的半径主要影响波散射的空间范围,多个blob造成的全场扰动显著增加。展开更多
In this paper, a novel junctionless field effect transistor（JLFET） is proposed. In the presence of a field plate between gate and drain, the gate-induced drain leakage（GIDL） effect is suppressed due to the decreas...In this paper, a novel junctionless field effect transistor（JLFET） is proposed. In the presence of a field plate between gate and drain, the gate-induced drain leakage（GIDL） effect is suppressed due to the decrease of lateral band-to-band tunneling probability. Thus, the off-state current Ioff, which is mainly provided by the GIDL current, is reduced. Sentaurus simulation shows that the Ioffof the new optimized JLFET is reduced by ～ 2 orders and its sub-threshold swing can reach76.8 mV/decade with little influence on its on-state current Ion, so its Ion/Ioff ratio is improved by 2 orders of magnitude compared with that of the normal JLFET. Optimization of device parameters such as Φfps（the work difference between field plate and substrate） and LFP（the length of field plate）, is also discussed in detail.展开更多
基金This study was financially supported by Beijing Education Commission,China.
文摘Growth and passivation of tunnels within Al foil by on-off controlling DC etching in 6 wt.% HCI solution has been investigated. It was found that, in a given etchant solution at a special temperature, the longest tunnel length was only a function of the turn-on interval of DC. The potential of Al foil broke at on-off controlling DC by the result from anode polarization curves and potential-time （E-t） responding curves. When DC was switched on, the potential increased abruptly over pitting potential, leading to nucleation of pits at the surface and the growth of tunnels at special length. When DC was switched off, the potential decreased rapidly to a passive value, leading to stoppage of nucleation and death of tunnels. By this way, the longest tunnel length can be controlled and a non-piercing layer can be obtained. Hence, etching of Al foil at this current is beneficial for maintaining a good mechanical strength.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10675043, 10575031 and 10675042）.
文摘The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied, A computer code for solving the Fokker-Planck equation in a toroidal geometry is developed and employed. The code is suitable for various auxiliary heating and current drive schemes in tokamak plasmas. The influence of the resonance regime on the current drive efficiency as well as the influence of trapped particle fraction on the current drive efficiency are emphasized. It is shown that, as an electrostatic force, the lower hybrid wave causes some of the trapped electrons to be untrapped and lose their energy, which can cut the LHCD efficiency by about 30%. The ITER scaling law is also used to estimate the trapped electron effects.
基金supported by the National Natural Science Foundation of China(Grant No.61704130)the Fundamental Research Funds for the Central Universities,China(Grant No.20101166085)the Opening Project of Key Laboratory of Microelectronic Devices&Integrated Technology from Institute of Microelectronics,Chinese Academy of Sciences(Grant No.90109162905)
文摘In this paper, a novel junctionless field effect transistor（JLFET） is proposed. In the presence of a field plate between gate and drain, the gate-induced drain leakage（GIDL） effect is suppressed due to the decrease of lateral band-to-band tunneling probability. Thus, the off-state current Ioff, which is mainly provided by the GIDL current, is reduced. Sentaurus simulation shows that the Ioffof the new optimized JLFET is reduced by ～ 2 orders and its sub-threshold swing can reach76.8 mV/decade with little influence on its on-state current Ion, so its Ion/Ioff ratio is improved by 2 orders of magnitude compared with that of the normal JLFET. Optimization of device parameters such as Φfps（the work difference between field plate and substrate） and LFP（the length of field plate）, is also discussed in detail.
