100-GeV large scale laser plasma electron acceleration by a multi-PW laser

We present three possible design options of laser plasma acceleration (LPA) for reaching a 100-GeV level energy by means of a multi-petawatt laser such as the 3.5-kJ, 500-fs PETawatt Aquitane Laser (PETAL) at French Alternative Energies and Atomic Energy Commission (CEA). Based on scaling of laser wakefield acceleration in the quasi-linear regime with the normalized vector potential a0 =1.4(1.6), acceleration to 100 (130) GeV requires a 30-m-long plasma waveguide operated at the plasma density n e ≈ 7×10 15 cm-3 with a channel depth Δn/ne = 20%, while a nonlinear laser wakefield accelerator in the bubble regime with a0≥2 can reach 100 GeV approximately in a36/a0-m-long plasma through self-guiding. The third option is a hybrid concept that employs a ponderomotive channel created by a long leading pulse for guiding a short trailing driving laser pulse. The detail parameters for three options are evaluated, optimizing the operating plasma density at which a given energy gain is obtained over the dephasing length and the matched conditions for propagation of relativistic laser pulses in plasma channels, including the self-guiding. For the production of high-quality beams with 1%-level energy spread and a 1π-mm-mradlevel transverse normalized emittance at 100-MeV energy, a simple scheme based on the ionization-induced injection mechanism may be conceived. We investigate electron beam dynamics and effects of synchrotron radiation due to betatron motion by solving the beam dynamics equations on energy and beam radius numerically. For the bubble regime case with a0=4, radiative energy loss becomes 10% at the maximum energy of 90 GeV.     

三维空间MIMO信道接收天线阵列互耦效应及系统容量分析

针对非频率选择性瑞利衰落MIMO(multiple-input multiple-output)信道,建立了接收天线阵列的三维空间信道模型,将MIMO的一般信道建模推广到三维空间域。在建模过程中利用天线阵列在互耦效应下的等效网络模型,推导出三维空间域模型下的互耦相关性的通用表达式,阐明了互耦效应下相关性与无互耦相关性之间的关系。应用通用表达式分析了当接收端为不同的天线阵列结构时,入射信号的中心到达角和角度扩展分别对于在互耦效应下信道容量的影响。分析结果验证了不同的角度扩展对于互耦相关性的影响,揭示了在互耦效应下影响系统容量的主要因素为入射信号的平均中心到达角。     

具有时间延迟积分(TDI)功能的288×4红外焦平面读出电路

提出了一种具有TDI功能的288×4扫描型红外焦平面读出电路.分析了TDI的工作原理及电路实现,给出了本类电路TDI功能的测试方法.实现了支持积分同时读出(IWR)的相关双采样(CDS)及其可测性设计.提出了一种大规模扫描型焦平面读出电路的低功耗设计方案.本文的设计结果经过了流片验证.     

一种快捕获宽调节范围的锁相环

提出了一种快捕获,低抖动,宽调节范围的增益自适应锁相环的设计.在这个方案中,采用了双边触发的鉴频鉴相器(dual-edge-triggered phase frequency detector)和自调节压控振荡器(self-regulated voltage controlled oscillator)并进行了详细的分析.芯片的加工工艺是0.5μm 1P3M CMOS标准数字逻辑工艺.测试结果表明输入频率变化在捕获范围的37%时,捕获时间为150ns;输出频率为640MHz时,均方根抖动为39ps.     

小灵通的技术现状及未来发展方向

小灵通(PHS)属于无绳电话，无绳通信的特点包括：利用无线电的通信方式，用户电话终端可不固定；PHS是固定市话网的延伸，依托于有线市话网，无需用户线；发射功率低、覆盖半径小．不能快速进行蜂窝小区切换，用户终端待机时间长，只适于低速移动漫游；采用数字技术，频谱利用率高．容量大；系统设备的配备较简单，成本低．容易被大众市场所接受。     

集成电路中多晶硅薄膜载流子迁移率的实验研究和理论模型

本文系统地研究了多晶硅薄膜载流子迁移率与掺杂浓度的关系,发现不仅如前人所指出的那样,多晶硅载流子迁移率在中等掺杂区有一极小值,而且同时在高掺杂区存在一个极大值.本文将前人提出的杂质分凝模型、晶粒间界陷阱模型和杂质散射机构结合起来,从理论上计算了极大值及其相应的掺杂浓度与晶粒大小、晶粒间界界面态密度的关系,并与实验结果进行了比较.理论模型较好地说明了实验结果.     

新的硅外延生长法—两段外延生长技术

一、序言近年来,随着集成电路的发展和固体器件的高频化,要求硅外延片的生长层厚度要很薄,且在与基片的界面处杂质分布很徒。这样的片子,在高速变容二极管、双极集成电路、高频晶体管或以PIN二极管、碰撞雪崩渡越时间二极管等为代表的微波二极管的制作中更是不可缺少。这些器件一般是在具有高浓度杂质的硅基片上或在掺杂了高浓度杂质的区域上生长具有低浓度杂质的硅外延层上制作的。一般,硅外延生长是利用调节掺杂气体的浓度或流量来控制杂质浓度。可是,在具有高浓度杂质的基片上生长具有低     

对拾音头用理想材料的追求

一、前言拾音头的特点之一是它在工作中受到机械力的作用而处于受迫振动状态,难以获得反馈用比较信号,只能以开环方式运用。因此,拾音头所采用的构件以及换能机制的性能直接在拾音头的各项性能中反映出来,研究和开发其     

Beta Decay of Neutron—Rich Nucleus ^208Hg

The β- decaying γ scheme of the neutron-rich nuclide 208Hg has been determined for the first time.The 208 Hg was produced in multi-nucleon transfer reaction taking place in the bombardment of 18O-beam on natural lead target,and the Hg-element products were sepaated with a gas-thermochromatography technique.The γ-ray single and γ-γ coincident spectra were measured.A partial 208 Hg γ scheme was proposed.Twenty-six γ rays were assigned to follow the β- decay of 208Hg.At the same time,a new level structure of the daughter nucleus 208 T1 was constructed,in which three new levels at 1.725MeV.1.652MeV,and 1.362MeV were affirmed.The experimental 208Tl level structure was compared with a shell-model calculation.