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Online Betatron Tune Feedback in the HLS-II Storage Ringby Siwei Wang, Wei Xu, Ke Xuan, Jingyi LiThe betatron tune of a storage ring is a critical parameter in the design process and for user operation. A proportional–integral–differential (PID)-based feedback system is developed for the Hefei light source II (HLS-II) storage ring to stabilize the betatron tune. This feedback system adopts a tune knob using global mechanism, which can precisely adjust the tune. A simulation using an intelligent algorithm is carried out to optimize the PID coefficients. Online experiments show that this system can effectively correct the tune shift, which is caused by the gap change of insertion devices and other factors. The tune feedback system can improve the tune stability to the order of $10^{-4}$ , which can be employed as a useful tool for stable operation of storage ring-based light sources. This paper reports the details of the development of this tune feedback system. Some simulation and online experiment results are also presented. more... |
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Total Ionizing Dose Responses of Forward Body Bias Ultra-Thin Body and Buried Oxide FD-SOI Transistorsby Qiwen Zheng, Jiangwei Cui, Liewei Xu, Bingxu Ning, Kai Zhao, Mingjie Shen, Xuefeng Yu, Wu Lu, Chengfa He, Diyuan Ren, Qi GuoThis paper investigates the total ionizing dose (TID) responses of forward body bias (FBB) ultrathin body and buried oxide fully depleted silicon-on-insulator (UTBB FD-SOI) transistors, which are commonly used in commercial foundries. The experimental results demonstrate that TID-induced threshold voltage shift in FBB nMOSFET cannot be mitigated by applying biasing to back-gate (back-gate biasing). Bias condition dependence has also been explored, revealing that building up of the oxide-trapped charge (Not) in the buried oxide is affected by the electric field induced by the space charge. Moreover, the effect of threshold voltage option on TID responses of UTBB FD-SOI transistors with the undoped channel was first explored. Finally, the TID-enhanced back-gate biasing controlling of the threshold voltage was observed, which is a new phenomenon for the TID responses of UTBB FD-SOI transistors. more... |
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Current Gain Degradation Model of Displacement Damage for Drift BJTsby Lei Li, Jian-Min Shi, Xu-Qiang Liu, Jian-Qun Yang, Xin-Wei Wang, Ze-Hong Li, Pu Zheng, Guang ZengDrift bipolar junction transistors (BJTs), characterized by a graded doping profile in the base region, are susceptible to the recombination in both the base and emitter–base depletion regions when they are damaged by atomic displacement, leading to the gain degradation. The previous model of the gain degradation of BJTs (i.e., Messenger–Spratt model) adopts the assumptions of the neutral base and ideal depletion, which are not valid for the drift BJTs. A drift BJT has an extra build-in electric field which breaks the neutral base condition, and the excess recombination rate is reduced and depends on the drift parameters. Furthermore, the nonideal depletion effects can suppress the excess recombination in the junction region, which will also reduce the susceptibility of the displacement damage (DD). This paper presents a physics-based improvement of the previous model and provides a much better fit to the experimental data of the 3CK3B drift BJTs subjected to deuterium–tritium 14-MeV neutron irradiation. The new model also suggests that the ideal factor of excess base current induced by DD approaches to 1.33 for the BJT technologies with narrow base or operated under low bias conditions. more... |
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A PUBLICATION OF THE IEEE NUCLEAR AND PLASMA SCIENCES SOCIETY |
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APRIL 2019 | VOLUME 66 | NUMBER 4 | IETNAE | (SSN 0018-9499) | ||
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