首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到14条相似文献,搜索用时 15 毫秒
1.
《Current Applied Physics》2015,15(7):780-783
In this study, we demonstrate the simulated subthreshold swing (SS) of silicon nanowire tunneling field-effect transistors (NWTFETs) by varying both the channel diameter from 10 nm to 40 nm and the gate coverage ratio from 30% to 100%. Our simulation work reveals that both a decrease in the channel diameter and an increase in the gate coverage ratio contribute to a reduction in the SS. Additionally, our work shows that the magnitude of the on-current depends linearly on the gate coverage ratio and that the drain current increases with a decrease in the channel diameter. Thus, an NWTFET with a channel diameter of 10 nm and a gate coverage ratio of 100% exhibits superior electrical characteristics over other silicon NWTFETs in that the NWTFET shows a point SS of 22.7 mV/dec, an average SS of 56.3 mV/dec, an on/off current ratio of ∼1013, and an on-current of ∼10−5 A/μm.  相似文献   

2.
同轴引出电子束相对论返波振荡器的粒子模拟   总被引:1,自引:4,他引:1       下载免费PDF全文
 设计了一种L波段同轴引出电子束相对论返波振荡器,采用KARAT 2.5维全电磁粒子模拟程序研究了器件内束-波作用的物理过程,分析了二极管电压和导引磁场对产生微波频率和束-波转换效率的影响。模拟结果表明:该器件在小型化,中等磁场的条件下具有较高的束-波作用效率。在电子束能量700 keV,电子束流10 kA,导引磁场为1.0 T时,器件在频率1.62 GHz处获得较高的微波输出,饱和后微波的平均功率达2.2 GW,平均效率约为30%,器件最大径向半径仅为5.0 cm。  相似文献   

3.
By using the Quantum Monte Carlo simulation; the electric properties of a nanowire, consisting of a ferroelectric core of spin-1/2 surrounded by a ferroelectric shell of spin-1/2 with ferro- or anti-ferroelectric interfacial coupling have been studied within the framework of the Transverse Ising Model (TIM). We have examined the effects of the shell coupling Js, the interfacial coupling JInt, the transverse field Ω, and the temperature T on the hysteresis behavior and on the electric properties of the system. The remanent polarization and the coercive field as a function of the transverse field and the temperature are examined. A number of characteristic behavior have been found such as the appearance of triple hysteresis loops for appropriate values of the system parameters.  相似文献   

4.
Weiji He  Yunfei Chen  Boyu Sima  Qian Chen  Guohua Gu 《Optik》2013,124(24):6559-6564
Single photon pulse ranging system with extremely high sensitivity has been widely used in distance measurement and 3D imaging. To analyze the factors that affect the measurement precision and accuracy will help to improve system performance. According to system structure and principle, we mainly discussed the following factors: laser intensity, pulse width, detection efficiency and time jitter. A simulation model based on Monte Carlo stochastic method was constructed in this paper, and we get the specific influence of factors on measurement precision and accuracy by simulation. Finally, we set up laboratory experiment system and took effective experiments on ranging precision and accuracy.  相似文献   

5.
设计了一种L波段同轴引出电子束相对论返波振荡器,采用KARAT 2.5维全电磁粒子模拟程序研究了器件内束-波作用的物理过程,分析了二极管电压和导引磁场对产生微波频率和束-波转换效率的影响。模拟结果表明:该器件在小型化,中等磁场的条件下具有较高的束-波作用效率。在电子束能量700 keV,电子束流10 kA,导引磁场为1.0 T时,器件在频率1.62 GHz处获得较高的微波输出,饱和后微波的平均功率达2.2 GW,平均效率约为30%,器件最大径向半径仅为5.0 cm。  相似文献   

6.
设计了一种能在C波段和X波段实现稳定双频输出的带有非对称谐振反射腔的单电子束同轴相对论返波振荡器。采用耦合阻抗跃变型慢波结构,使用粒子PIC模拟软件进行了粒子模拟研究。模拟结果显示:轴向电场在系统中的分布得到改进,电子束的能散得到改善。在电子束电压511 kV,电流8.95 kA,引导磁场0.73 T的条件下,双频器件实现了8.09 GHz和9.91 GHz的双波段频率稳定输出,平均功率为1.0 GW,波束互作用效率为21.9%, 效率高于空心双波段返波管及其他双波段器件。器件辐射功率的拍频为1.82 GHz,拍波更为明显和稳定。模拟研究中同时发现, 随着慢波结构之间漂移段的变化,双频频率都呈现一种准周期的变化。  相似文献   

7.
研究了一种能够同时产生C波段和X波段微波、具有双电子束结构的相对论返波振荡器,采用嵌套式的高频结构将两个波段的束-波相互作用空间隔离开来,从而使两个波段的束-波相互过程互不影响。当二极管电压为650 kV、内外环形电子束流分别为5.4,6.4 kA、导引磁场为2.2 T时,两个波段微波的频率分别为4.625,8.450 GHz,模拟产生的微波功率分别为920,600 MW,转换效率约为21.8%,17.1%。并采用粒子模拟法研究了导引磁场、二极管电压及两个束-波相互作用区关键结构参数对器件运行的影响,给出了双波段微波功率、频率随导引磁场、二极管电压等参数的变化曲线。  相似文献   

8.
 设计了一种带有反射腔的能在X波段实现稳定双频输出的圆柱结构相对论返波管,采用2.5维相对论全电磁PIC粒子模拟软件行粒子模拟研究。仿真结果表明:在输入电压433 kV、引导磁场2.2 T的条件下,实现了9.53,10.09 GHz的双频稳定输出,平均输出功率340 MW,平均功率效率24.1%。  相似文献   

9.
研究了一种能够同时产生C波段和X波段微波、具有双电子束结构的相对论返波振荡器,采用嵌套式的高频结构将两个波段的束-波相互作用空间隔离开来,从而使两个波段的束-波相互过程互不影响。当二极管电压为650kV、内外环形电子束流分别为5.4,6.4kA、导引磁场为2.2T时,两个波段微波的频率分别为4.625,8.450GHz,模拟产生的微波功率分别为920,600MW,转换效率约为21.8%,17.1%。并采用粒子模拟法研究了导引磁场、二极管电压及两个束-波相互作用区关键结构参数对器件运行的影响,给出了双波段微波功率、频率随导引磁场、二极管电压等参数的变化曲线。  相似文献   

10.
设计了一种带有反射腔的能在X波段实现稳定双频输出的圆柱结构相对论返波管,采用2.5维相对论全电磁PIC粒子模拟软件行粒子模拟研究。仿真结果表明:在输入电压433 kV、引导磁场2.2 T的条件下,实现了9.53,10.09 GHz的双频稳定输出,平均输出功率340 MW,平均功率效率24.1%。  相似文献   

11.
《中国物理 B》2021,30(5):56101-056101
The mechanical property and deformation mechanism of twinned gold nanowire with non-uniform distribution of twinned boundaries(TBs) are studied by the molecular dynamics(MD) method. It is found that the twin boundary spacing(TBS) has a great effect on the strength and plasticity of the nanowires with uniform distribution of TBs. And the strength enhances with the decrease of TBS, while its plasticity declines. For the nanowires with non-uniform distribution of TBs, the differences in distribution among different TBSs have little effect on the Young's modulus or strength, and the compromise in strength appears. But the differences have a remarkable effect on the plasticity of twinned gold nanowire. The twinned gold nanowire with higher local symmetry ratio has better plasticity. The initial dislocations always form in the largest TBS and the fracture always appears at or near the twin boundaries adjacent to the smallest TBS. Some simulation results are consistent with the experimental results.  相似文献   

12.
We analyse the performance of the explicit algebraic subgrid-scale (SGS) stress model (EASSM) in large eddy simulation (LES) of plane channel flow and the flow in a channel with streamwise periodic hill-shaped constrictions (periodic hill flow) which induce separation. The LESs are performed with the Code_Saturne which is an unstructured collocated finite volume solver with a second-order spatial discretisation suitable for LES of incompressible flow in complex geometries. At first, performance of the EASSM in LES of plane channel flow at two different resolutions using the Code_Saturne and a pseudo-spectral method is analysed. It is observed that the EASSM predictions of the mean velocity and Reynolds stresses are more accurate than the conventional dynamic Smagorinsky model (DSM). The results with the pseudo-spectral method were, in general, more accurate. In the second step, LES with the EASSM of flow separation in the periodic hill flow is compared to LES with the DSM, no SGS model and a highly resolved LES data using the DSM. Results show that the mean velocity profiles, the friction and pressure coefficients, the length and shape of the recirculation bubble, as well as the Reynolds stresses are considerably better predicted by the EASSM than the DSM and the no SGS model simulations. It was also observed that in some parts of the domain, the resolved strain-rate and SGS shear stress have the same sign. The DSM cannot produce a correct SGS stress in this case, in contrast to the EASSM.  相似文献   

13.
王蓬  田修波  汪志健  巩春志  杨士勤 《物理学报》2011,60(8):85206-085206
采用三维粒子模拟模型研究了有限尺寸方靶等离子体浸没离子注入过程中的鞘层动力学行为,得到了鞘层尺寸和方靶表面的注入剂量、注入能量以及注入角度等信息,并与二维无限长方靶注入结果进行了对比.模拟结果表明,与无限长方靶不同,有限尺寸方靶周围鞘层很快扩展为球形,但鞘层厚度明显减小.在模拟的50ω-1pi时间尺度内靶表面注入剂量很不均匀,中心区域注入剂量最小,四个边角附近位置注入剂量最大.这种剂量不均匀性是由于鞘层扩展为球形,使得鞘层内离子被聚焦并注入到边角附 关键词: 等离子体浸没离子注入 数值模拟 三维粒子模拟 有限尺寸方靶  相似文献   

14.
熊豪 《大学物理》2007,26(10):57-59
以黑洞为例,在不考虑满足幺正性的情况下得到了在背景辐射中Schwarzschild黑洞的质量随时间变化的微分方程,并对该方程进行了必要的研究和讨论,作为对《新概念物理教程.力学》和《新概念物理教程.热学》中提到的负热容量系统的不稳定性的另一个注释.文章最后用Runge-Kutta法数值模拟了Schwarzschild黑洞的质量演化过程,使广大学生能够更直观地理解这一过程.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号