薄膜型平栅极FED背光源的制备及性能研究

利用磁控溅射和光刻技术在玻璃基底上制备薄膜型平栅极场发射阴极阵列,采用电泳工艺将碳纳米管(CNTs)发射材料转移到薄膜型平栅结构的阴极电极表面,借助光学显微镜和扫描电镜观测薄膜型平栅极场发射阴极阵列。利用Ansys软件模拟阴栅间距对阴极表面电场分布的影响,优化其结构参数,对其场发射特性进行了讨论。实验结果表明,CNTs能均匀地分散在平栅型结构的阴极表面,当电场强度为2.4 V/μm时,器件发射电流密度达到1.8 mA/cm2,亮度达3 000cd/m2,均匀性为90%,能稳定发射28 h,且具有较好的栅控作用。该薄膜型平栅极背光源技术简单、成本低,为将来制备新一代大面积场发射背光源提供了可行性方案。

平栅型氧化锡表面传导电子发射源的制备及场发射性能研究

利用磁控溅射、光刻和剥离技术在玻璃基底上成功制备了平栅型氧化锡表面传导电子发射源，并测试其场发射性能。扫描电镜和光学显微镜测试表明，沉积在阴极和栅极之间的氧化锡为不连续薄膜，直径大约在100～200nm。场发射测试表明，电子发射源的传导电流和发射电流完全被栅压控制。在阳压和栅压分别为3200V和210V时，阴阳间距为500μm时，平栅型氧化锡表面传导电子发射源的电子发射效率为0．85％，发光亮度为850ed／m2，表明氧化锡薄膜在表面传导电子发射源方面有着较好的应用潜力。

平栅型双层膜的场致发射性能研究

通过在平栅型基板上,分别溅射氧化铋薄膜和氧化锡薄膜,形成阴极场发射阵列,并在阴极和栅极之间加载脉冲电流,使阴栅级之间的薄膜形成裂缝,并进行场致发射性能测试,测试结果表明,平栅型双层膜发射器件的开启电压随阳极电压增加而降低。在阳压为3000 V,隔离子高度为500μm时,平栅型双层膜场发射器件的开启电压为110 V,在栅压为110 V时的发射效率为1%左右,随着栅压的增大,发射效率逐渐减小。该双层膜阴极具有均匀的发射性能、良好的栅控能力以及场发射特性。

电泳法制备平栅极碳纳米管场发射阴极及场发射特性研究

采用电泳法在ITO玻璃基板上选择性制备了碳纳米管(CNTs)阴极薄膜,采用电子扫描(SEM)分析了CNTs薄膜的表面形貌,并测试了碳纳米管阴极的场致发射特性。结果表明,利用电泳法制得的碳纳米管阴极薄膜均匀性、致密性良好,且具有较大发射电流密度;通过控制共面栅控CNTs场发射阴极的栅极电位能够有效控制阴极的场发射电流密度。当阳极电压为450 V,栅极电压230 V时,发射电流密度达到7.6 mA/cm2。

透平跨音速叶栅的优化设计

将遗传算法用于透平跨音速叶栅的优化设计，提出了相应的数学模型和优化方法。优化算例表明，本文所提出的模型及算法能有效的优化叶型方案，避免了一般优化算法的局部最优或维数灾难问题，从而在新的领域内将优化计算在叶轮机械设计中的应用进行了有益的探索。

应用于LCD的平栅型碳纳米管场致发射显示器背光源的研制

采用磁控溅射、光刻和湿法刻蚀技术制备平栅型场发射阴极阵列,利用电泳将碳纳米管(CNT)发射源沉积在阴极表面,将阴极板和阳极板封接后制成51 cm单色平栅型CNT场致发射显示器(CNT-FED),作为背光源模板应用于49 cm液晶显示器(LCD)器件中。场发射测试表明,器件在阳极电压3 500 V、栅极电压290 V时,阳极电密度高达81.3μA/cm2,最高亮度可达7000 cd/m2,均匀性为96%;稳定发射7 h后,发射电流无明显衰减。以背光源形式应用于49 cm×25.4 mm LCD器件,亮度可达205 cd/m2。

Static Induction Devices with Planar Type Buried Gate

Based on the surface-gate and buried-gate structures,a novel buried-gate structure called the planar type buried-gate (PTBG) structure for static induction devices (SIDs) is proposed.An approach to realize a buried-gate type static induction transistor by conventional planar process technology is presented.Using this structure,it is successfully avoided the second epitaxy with a high degree of difficulty and the complicated mesa process in conventional buried gate.The experimental results demonstrate that this structure is desirable for application in power SIDs.Its advantages are high breakdown voltage and blocking gain.

A High Performance Sub-100nm Nitride/Oxynitride Stack Gate Dielectric CMOS Device with Refractory W/TiN Metal Gates

By complementing the equivalent oxide thickness （EOT） of a 1.7nm nitride/oxynitride （N/O） stack gate dielectric （EOT- 1.7nm） with a W/TiN metal gate electrode,metal gate CMOS devices with sub-100nm gate length are fabricated in China for the first time. The key technologies adopted to restrain SCE and to improve drive ability include a 1.7nm N/O stack gate dielectric, non-CMP planarization technology, a T-type refractory W/TiN metal stack gate electrode, and a novel super steep retrograde channel doping using heavy ion implantation and a double sidewall scheme. Using these optimized key technologies, high performance 95nm metal gate CMOS devices with excellent SCE and good driving ability are fabricated. Under power supply voltages of VDS ± 1.5V and VGS± 1.8V,drive currents of 679μA/μm for nMOS and - 327μA/μm for pMOS are obtained. A subthreshold slope of 84.46mV/dec, DIBL of 34.76mV/V, and Vth of 0.26V for nMOS, and a subthreshold slope of 107.4mV/dec,DIBL of 54.46mV/V, and Vth of 0.27V for pMOS are achieved. These results show that the combined technology has indeed thoroughly eliminated the boron penetration phenomenon and polysilicon depletion effect ,effectively reduced gate tunneling leakage, and improved device reliability.

Free electron laser based on the Smith-Purcell radiation

A Smith-Purcell （SP） free electron laser （FEL） ,composed of a metallic diffraction flat grating,an open cylindrical mirror cavity and a relativistic sheet electron beam with moderate energy, is presented. The characteristics of this device are studied by theoretical analysis,experimental measurements and particle-in-cell （PIO） simulation method. Results indicate that the coherent radiation with an output peak power up to 50 MW at millimeter wavelengths can be generated by using relativistic electron beam of moderate energy.

Induced Matching Number of the Plane Grid Graph

An induced matching M in a graph G is a matching such that V(M) induces a 1-regular subgraph of G. The induced matching number of a graph G, denoted by I M(G), is the maximum number r such that G has an induced matching of r edges. Induced matching number of Pm×Pn is investigated in this paper. The main results are as follows:(1) If at least one of m and n is even, then IM(Pm×Pn=[(mn)/4].(2) If m is odd, then

Path Planning for Lunar Surface Robots Based on Improved Ant Colony Algorithm

In the real-world situation,the lunar missions’scale and terrain are different according to various operational regions or worksheets,which requests a more flexible and efficient algorithm to generate task paths.A multi-scale ant colony planning method for the lunar robot is designed to meet the requirements of large scale and complex terrain in lunar space.In the algorithm,the actual lunar surface image is meshed into a gird map,the path planning algorithm is modeled on it,and then the actual path is projected to the original lunar surface and mission.The classical ant colony planning algorithm is rewritten utilizing a multi-scale method to address the diverse task problem.Moreover,the path smoothness is also considered to reduce the magnitude of the steering angle.Finally,several typical conditions to verify the efficiency and feasibility of the proposed algorithm are presented.

Novel Nano-scale Overlay Alignment Method for Room-temperature Imprint Lithography

A novel nano-scale alignment technique based on Moiré signal for room-temperature imprint lithography in the submicron realm is proposed. The Moiré signals generated by a pair of quadruple gratings on two templates respectively are optically projected onto a photodetector array, then the detected Moiré signals are used to estimate the alignment errors in x and y directions. The experiment result indicates that complex differential Moiré signal is sensitive to relative displacement of the pair of marks than each single Moiré signal, and the alignment resolutions obtained in x and y directions are ±20nm(3σ) and ±24nm(3σ). They can meet the requirement of alignment accuracy for submicron imprint lithography.

Special Apodized Fiber Bragg Grating for Flat-top Band-pass Reflectivity Filter

The characteristics of special apodized fiber Bragg grating (FBG) in flat-top pass-band as reflectivity filter are presented. This special apodized FBG was designed by the particle swarm optimization algorithm. Compared with conventional apodized FBG, the special apodized FBG presented was more robust in the flat-top pass-band characteristic even if the strength of grating is very week. This technology is very interesting in designing the filter for wavelength division multiplexing system.

Estimation of Moire Patterns Using Spectral Trajectories in the Complex Plane

The authors found equations for complex coordinates of spectral peaks and trajectories in the case of two superposed layers, each consisting of two orthogonal gratings. The number of geometric elements in spectra was found for four running parameters and different number of gratings by layers. The shape of trajectories was determined in the corresponding cases. The relationships between parameters were found which could help in reducing the intervals of parameters, in particular the relationship between the inverse aspect ratios. The numerical simulation and the physical experiment were in a good agreement with the theory. The proposed technique seems to be helpful in estimation of occurrence of moir6 patterns in visual displays which makes possible the minimization in the spectral domain without calculation of spectra.

Measurement and Analysis of Movement of BPM Vacuum Chamber for HLS

The beam horizontal orbit at Hefei Light Source(HLS)was drifting all along while the storage ring was operating.To study this phenomenon,the displacement and the temperature variation of the BPM chamber were measured.By analyzing the measurement results,the main reason that explained the drifting phenomenon was found. The vacuum chamber following the dipole magnets was heated by the synchrotron light,which caused the increasing of the chamber surface temperature.The variation of the chamber temperature was the main reason why the BPM chamber held the horizontal displacement.To suppress the orbit drifting,a compensation method of BPM movement was proposed and its experimental results were given.

Aerodynamic inverse design optimization for turbine cascades based on control theory

Based on control theory,adjoint system for the general problem of turbomachinery aerodynamic optimization was studied and developed in the present paper by using the variation technique in the grid node coordinates combined with Jacobian Matrics of flow fluxes.Then the adjoint system for aerodynamic design optimization of turbine cascade governed by compressible Navier-Stokes equations was derived in detail.With the purpose of saving computation resources,the mathematic method presented in this paper avoids the coordinate system transforming in the traditional derivation process of the adjoint system and makes the adjoint system much more sententious.Given the general expression of objective functions consisting of both boundary integral and field integral,the adjoint equations and their boundary conditions were derived,and the final expression of the objective function gradient including only boundary integrals was formulated to reduce the CPU cost,especially for the complex 3D configurations.The adjoint system was solved numerically by using the finite volume method with an explicit 5-step Runge-Kutta scheme and Riemann approximate solution of Roe's scheme combined with multi-grid technique and local time step to accelerate the convergence procedure.Finally,based on the aerodynamic optimization theory in the present work,2D and 3D inviscid and viscous inverse design programs of axial turbomachinery cascade for both pressure distribution and isentropic Mach number distribution on the blade wall were developed,and several design optimization cases were performed successfully to demonstrate the ability and economy of the present optimization system.

Aerodynamic Loading Distribution Effects on the Overall Performance of Ultra-High-Lift LP Turbine Cascades

The present paper reports the results of an experimental investigation aimed at comparing aerodynamic perform- ance of three low-pressure turbine cascades for several Reynolds numbers under steady and unsteady inflows. This study is focused on finding design criteria useful to reduce both profile and secondary losses in the aero-engine LP turbine for the different flight conditions. The baseline blade cascade, characterized by a standard aerodynamic loading （Zw=1.03）, has been compared with two Ultra-High-Lift profiles with the same Zweifel number （Zw=1.3 for both cascades）, but different velocity peak positions, leading to front and mid-loaded blade cascade configurations. The aerodynamic flow fields downstream of the cascades have been experimentally in- vestigated for Reynolds numbers in the range 70000〈Re〈300000, where lower and upper limits are typical of cruise and take-off/landing conditions, respectively. The effects induced by the incoming wakes at the reduced frequency ./＋=0.62 on both profile and secondary flow losses for the three different cascade designs have been studied. Total pressure and velocity distributions have been measured by means of a miniaturized 5-hole probe in a tangential plane downstream of the cascade for both inflow conditions. The analysis of the results allows the evaluation of the aerodynamic performance of the blade cascades in terms of profile and secondary losses and the understanding of the effects of loading distribution and Zweifel number on secondary flows. When operating un- der unsteady inflow, contrarily to the steady case, the mid-loaded cascade has been found to be characterized by the lowest profile and secondary losses, making it the most attractive solution for the design of blades working in real conditions where unsteady inflow effects are present.

Multigrid Navier-Stokes Calculation for Two Dimensional Cascades

A fast and accurate numerical method for solving the two dimensional Reynolds aveaged Navier Stokes is applied to calculate the internal fluid of turbines and compressors. The code is based onan explicit, time-marching, finite volume technique. In order to accelerate convergence, local time stepping, multigrid method is employed. Four stage Runge-Kutta method is implemented to extend the stability domain. Test cases of Hobson’s impulse cascade, NASA Rotor 37 and Sanz’s supercritical compressor cascade are presented. Results of Mach number distribution on blade surfaces and Mach number contour plots indicate good agreement with experimental data. Compared with full three 3D Navier-Stokes (N-S) codes, the two dimensional code only takes a short time to obtain predicted results. This code can be used widely in practical engineering design.

Numerical Investigation on Wet Steam Non-equilibrium Condensation Flow in Turbine Cascade

Based on the two-phase wet steam flow with spontaneous condensation, experimental verification and flow analysis on nozzle and 2D cascade are carried out. The 3D Reynolds-Averaged gas-liquid two-phase flow control equation solver is explored with k-e-kp turbulence model. Furthermore, 3D flow numerical simulation on the last stage stator of the steam turbine is carried out. The results show that a sudden pressure rise on blade suction surface is mainly caused by the droplet growth in condensation flow. The more backward the condensation position is in cascade passage, the less the sudden pressure rise from condensation is, and the larger the nucleation rate is, the maximum under-cooling and the number of droplets per unit volume are. Interaction of condensation wave and shock wave has imposed greater influence on the parameters of the blade cascade outlet.

Effects Of Average Index Variation in Apodized Long-Period Fiber Gratings

We analyze the effects of average index variation on the transmission characteristics of an index-apodized long-period fiber grating （LPFG） by the transfer matrix method and study how these effects depend on the grating length, the grating profile, the modal dispersion factor, and the duty cycle of the index modulation. Apart from shifting the resonance wavelength and modifying the rejection band, average index variation can give rise to significant side lobes that may appear on the short-wavelength or long-wavelength side of the rejection band, depending on the signs of the average index change and the modal dispersion factor. Our results provide general guidance for the writing of LPFGs for the minimization of side lobes. Our analysis compares well with published experimental results and should be useful for the design and fabrication of LPFGs.