共查询到20条相似文献,搜索用时 155 毫秒
1.
2.
针对北京正负电子对撞机II期(BEPC II)直线加速器升级改造过程中束流位置探测器(BPM)电子学对外部触发信号的需求,设计了一台高精度延时控制、上升时间短和参数灵活调节的数字延时触发器。采用FPGA(现场可编程门阵列)作为主控制器展开设计,重点介绍了基于FPGA的边沿检测模块和多通道延时处理模块的设计与仿真,描述了FPGA和驱动电路的设计方案以及在直线加速器上的应用。经测试,延时可调范围4 ns^4μs,最小步进4 ns,步进误差0.125%;上升时间2 ns,延时抖动135.4 ps。 相似文献
3.
4.
5.
针对典型n+-p-n-n+结构的双极晶体管,从器件内部电场强度、电流密度和温度分布变化的分析出发,研究了在强电磁脉冲(electromagnetic pulse,EMP)作用下其内在损伤过程与机理.研究表明,双极晶体管损伤部位在不同幅度的注入电压作用下是不同的,注入电压幅度较低时,发射区中心下方的集电区附近首先烧毁,而在高幅度注入电压作用下,由于基区-外延层-衬底构成的PIN结构发生击穿,导致靠近发射极一侧的基极边缘处首先发生烧毁.利用数据分析软件,对不同注入电
关键词:
双极晶体管
强电磁脉冲
器件损伤
损伤功率 相似文献
6.
本文建立了时变非磁化等离子体平板的一维模型,并采用时域有限差分(FDTD)方法对太赫兹(THz)电磁波在时变等离子体中传播时的反射、透射系数及吸收率进行了计算.然后根据计算结果分析了时变等离子体的上升时间、电子密度、温度以及等离子体平板厚度等参数对不同频段THz波在等离子体中传播特性的影响.分析结果表明:THz波在时变等离子体中传播时,其反射系数受等离子体电子密度和上升时间的影响较大;而吸收率则随着上升时间的减小、电子密度及平板厚度的增加而增大;此外,THz电磁波能够穿透量级为1020m-3的高密度等离子体层,可以作为再入段飞行器通信以及高密度等离子体诊断的理想工具. 相似文献
7.
8.
利用有源传输线模型与漂移-扩散模型的耦合计算模型,对在瞬态X射线辐照下电缆末端典型N+-p-n-N+结构的双极晶体管负载的毁伤效应与规律进行研究,通过分析双极晶体管内部晶格温度分布,判定是否处于毁伤状态,总结双极晶体管烧毁时间和烧毁所需能量与脉冲X射线脉冲宽度和注量之间的关系。结果表明:随着脉冲X射线脉宽增加,双极晶体管烧毁能量变化较小,烧毁时间逐渐增加;随着注量增加,烧毁时间逐渐降低,在5.86J/cm2以下时,烧毁所需能量基本相同,之后呈指数逐渐增加,并通过曲线拟合得到损伤规律的经验公式。 相似文献
9.
建立了双极晶体管(BJT)在强电磁脉冲作用下的二维电热模型, 对处于有源放大区的BJT在基极注入强电磁脉冲时的瞬态响应进行了仿真. 结果表明, BJT烧毁点位置随注入脉冲幅度变化而变化, 低脉冲幅度下晶体管烧毁是由发射结反向雪崩击穿所致, 烧毁点位于发射结柱面区; 而在高脉冲幅度下, 由基区-外延层-衬底组成的p-n-n+ 二极管发生二次击穿导致靠近发射极一侧的基极边缘率先烧毁; BJT的烧毁时间随脉冲幅度升高而减小, 而损伤能量则随之呈现减小-增大-减小的变化趋势, 因而存在一个极小值和一个极大值. 仿真与实验结果的比较表明, 本文建立的晶体管模型不但能预测强电磁脉冲作用下BJT内部烧毁发生的位置, 而且能够得到损伤能量.
关键词:
双极晶体管
强电磁脉冲
烧毁点位置
损伤能量 相似文献
10.
《中国光学与应用光学文摘》2005,(2)
O433.4 2005020906 禄丰老长菁恐龙化石的XRD和RS分析=Analysis of di- nosaur fossils and fossil formed from Laochangqing Valley Lufeag County by XRD and RS[刊,中]/杨群(云南省楚雄 师院物理与电子科学系.云南,楚雄(675000)),王怡林… //光电子·激光.-2004,15(11).-1365-1368 运用X射线衍射(XRD)、激光显微喇曼光谱(RS)和 光学偏光显微镜等检测方法,研究分析了云南省禄丰县老 长箐地区的5个早、中侏罗纪时期的恐龙化石样品。实验 相似文献
11.
针对前照式有源型可见光互补金属氧化物半导体(CMOS)器件,开展了1080nm连续激光与1064nm单脉冲ns激光损伤效应的对比研究,观察到了CMOS出现点损伤、半边黑线损伤与十字交叉黑线损伤三个典型的硬损伤阶段,并分析了损伤机理。在连续激光辐照下,损伤效应主要是热效应的影响。当辐照时间小于稳态时间时,辐照时间越长,损伤阈值越低,当辐照时间大于稳态时间时,损伤阈值趋于稳定值。对损伤后的CMOS器件的微观结构进行了显微观察,结合CMOS电路结构深入分析了各种典型实验现象的损伤机理,半边黑线损伤与十字交叉黑线损伤主要是不同层金属线路熔断导致信号断路。在单脉冲ns激光作用下,CMOS像元表面的硬损伤主要是激光加热作用和等离子体冲击波作用引起的。 相似文献
12.
DPF-300脉冲X射线源的同步触发系统采用三级触发:第一级由初级脉冲产生器触发氢闸流管;第二级由氢闸流管输出脉冲触发多路触发开关;第三级由多路触发开关和触发箱组成,触发主放电场畸变开关。该触发系统中多路触发开关产生负极性脉冲信号,通过耦合电容,到达开关的触发脉冲上升沿,约为40 ns,脉冲半高宽约60 ns,上升陡度大于0.67 kV/ns。能够同时触发40个同轴型场畸变开关,电压工作范围20~40 kV,不同发次触发箱输出的触发脉冲信号时间分散性小于4 ns,同一发次不同开关的放电时间分散性小于20 ns。在工作电压20 kV,主放电开关充0.115 MPa氮气时,整机负载电流达到约1 MA。 相似文献
13.
In this paper, knotted objects (RS vortices) in the theory of
topological phase singularity in electromagnetic field have been
investigated in details. By using the Duan's topological current theory,
we rewrite the topological current form of RS vortices and use this topological
current we reveal that the Hopf invariant of RS vortices is just the
sum of the linking and self-linking numbers of the knotted RS
vortices. Furthermore, the conservation of the Hopf invariant in the
splitting, the mergence and the intersection processes of knotted RS
vortices is also discussed. 相似文献
14.
S B Leder J B Spitzer P Milner C Flevaris-Phillips F Richardson J C Kirchner 《The Journal of the Acoustical Society of America》1986,79(6):1967-1974
Acoustic correlates of contrastive stress, i.e., fundamental frequency (F0), duration, and intensity, and listener perceptions of stress, were investigated in a profoundly deaf subject (RS) pre/post single-channel cochlear implant and longitudinally, and compared to the overall patterns of age-peer profoundly deaf (JM) and normally hearing subjects (DL). The stimuli were a group of general American English words in which a change of function from noun to verb is associated with a shift of stress from initial to final syllable, e.g., CON'trast versus conTRAST'. Precochlear implant, RS was unable to produce contrastive stress correctly. Hearing one day post-stimulation resulted in significantly higher F0 for initial and final stressed versus unstressed syllables. Four months post-stimulation, RS maintained significantly higher F0 on stressed syllables, as well as generalization of significantly increased intensity and longer syllable duration differences for all stressed versus unstressed syllables. Perceptually, listeners judged RS's contrastive stress placement as incorrect precochlear implant and as always correct post-cochlear implant. JM's contrastive stress was judged as 96% correct, and DL's contrastive stress placement was 100% correct. It was concluded that RS reacquired all acoustic correlates needed for appropriate differentiation of contrastive stress with longitudinal use of the cochlear implant. 相似文献
15.
Hexagonal boron nitride (hBN), due to its high reliability as a two-dimensional (2D) dielectric material, has attracted much attention for its potential applications in nanoelectronic devices. Here, the use of radio frequency (RF) magnetron sputtering-grown hBN films to construct hBN-based resistive switching (RS) memory device is reported, and the RS mechanism is deduced. The hBN-based RS memory shows low operating voltage, reproducible write cycles, and long retention time. First-principles simulations further confirm the resistive switching. This work provides an important case to facilitate the future applications of 2D materials in the RS memory. 相似文献
16.
J Gaudin C Ozkan J Chalupský S Bajt T Burian L Vyšín N Coppola SD Farahani HN Chapman G Galasso V Hájková M Harmand L Juha M Jurek RA Loch S Möller M Nagasono M Störmer H Sinn K Saksl R Sobierajski J Schulz P Sovak S Toleikis K Tiedtke T Tschentscher J Krzywinski 《Optics letters》2012,37(15):3033-3035
The interaction of free electron laser pulses with grating structure is investigated using 4.6±0.1 nm radiation at the FLASH facility in Hamburg. For fluences above 63.7±8.7 mJ/cm2, the interaction triggers a damage process starting at the edge of the grating structure as evidenced by optical and atomic force microscopy. Simulations based on solution of the Helmholtz equation demonstrate an enhancement of the electric field intensity distribution at the edge of the grating structure. A procedure is finally deduced to evaluate damage threshold. 相似文献
17.
In this paper we discuss the properties of the general covariant angular momentum of a five-dimensional brane-world model. Through calculating the total angular momentum of this model, we are able to analyze the properties of the total angular momentum in the inflationary RS model. We show that the space-like components of the total angular momentum of the inflationary RS model are all zero while the others are non-zero, which agrees with the results from ordinary RS model. 相似文献
18.
In this paper we discuss the properties of the general covariant angular momentum of a fivedimensional brane-world model. Through calculating the total angular momentum of this model, we are able to analyze the properties of the total angular momentum in the inflationary RS model. We show that the space-like components of the total angular momentum of the inflationary RS model are all zero while the others are non-zero, which agrees with the results from ordinary RS model. 相似文献
19.
20.
运用第一性原理平面波赝势和广义梯度近似方法, 对闪锌矿结构(ZB)和氯化钠结构(RS) ZnS的状态方程及其在高压下的相变进行计算研究, 分析相变点附近的电子态密度、能带结构和光学性质的变化机理. 结果表明: 通过状态方程得到ZB相到RS相的相变压强值为18.1 GPa, 而利用焓相等原理得到的相变压强值为18.0 GPa; 在结构相变过程中, sp3轨道杂化现象并未消失, RS相ZnS的金属性明显增强; 与ZB相ZnS相比, RS相ZnS的介电常数主峰明显增强, 并向低能方向出现了明显偏移, 使得介电峰向低能方向拓展, 在低能区电子跃迁大大增强.
关键词:
硫化锌
相变
电子结构
光学性质 相似文献