微空心阴极放电与准分子光源

微空心阴极放电是一种新颖的、非平衡、高气压辉光放电.综述了微空心阴极放电的基本原理;详细论述了微空心阴极放电中的准分子辐射,以及微空心阴极放电的放电方式(直流放电、脉冲放电、射频放电)对准分子辐射强度和效率的影响;最后论述了微空心阴极放电的运行方式(串联运行、并联运行)对准分子辐射的影响.     

CO2激光诱导大气放电特性的研究

为了研究脉冲CO₂激光诱导空气放电的特性,建立了高压电容充放电实验平台,采用间距为8mm、半径为10mm的一对球形石墨电极,取得了放电电压和电流的实时数据,采用2阶振荡电路模型对放电电压和放电电流进行拟合得到了电极间激光诱导放电等离子体的阻抗,并对放电时间、放电延时及抖动做了统计。结果表明,激光诱导放电等离子体的阻抗很小,约1Ω~2Ω,拟合得到的放电等离子体阻抗随放电电压、放电电容、以及激光能量的增加而减小;放电延时随着实验条件的变化在2μs~10μs之间变化,放电延时以及延时抖动随着放电电压和激光能量的增加而降低,而受放电电容大小的影响不明显。由此高稳定性的激光脉冲和高压有助于激光诱导放电过程的稳定。     

新颖的微空心阴极放电及其性质研究

介绍了微空心阴极放电(microhollow cathode discharge,简称MHCD)的特点,根据MHCD的基本结构设计了—种新的放电结构:它由一个电源和一个可变电阻器构成“微空心阴极维持的辉光放电”,MHCD作为放电的阴极,金属针作为放电的阳极。利用该放电结构进行了空气的放电实验,产生了高气压大体积高电流密度的辉光放电等离子体,用于工业上的多种等离子体加工中;如果用稀有气体放电则能够用来作为微型准分子激光器的增益介质。在200Torr气压下,获得了稳定的空气直流放电,等离子体中电子密度估计在1011到1012cm-3之间,测得放电电流范围;8mA-30mA。测得放电V-I特性曲线,它有典型的微空心阴极维持的辉光放电的特点.估计的气体放电温度为2000K左右。     

两种电容快速放电方法研究

电容使用完成后必须对其进行放电,以保证使用者的安全和延长电容的使用寿命。传统电容放电方式是采用自然放电或连接恒定电阻放电,对于大电容、高电压的电容需较长的放电时间。为提升电容放电速率,提出了两种快速放电法。增大放电电流,改变放电过程中放电电阻的阻值,保证放电电流保持在较高水平,从而大幅减少放电时间。结果表明,采用电机控制放电电阻随时间均匀变化可达到最快的放电速率,比连接恒定电阻的放电速率提升5倍左右;采用继电器控制放电电阻阻值阶跃变化可提升电容放电速率,比连接恒定电阻放电速率提升1倍左右。     

不同气压条件下空气介质阻挡放电的特性

建立了一套放电装置,放电室内的空气压力可调。设计并制作了单面梳状和平行双平面两种电极板,在不同气压环境下进行空气介质阻挡放电实验。拍摄记录了放电现象,采用电荷-电压(q-V)法处理了放电的有关测量数据,对实验结果进行了分析。研究结果表明,空气介质阻挡放电的特性变化与放电环境气压有关。在各种气压条件下,该文的介质阻挡放电均呈脉冲群间歇性;随着放电环境气压减小,放电由常压下的粗大流注电晕逐渐变成细而密集的细丝状微流注电晕,直至融合为貌似辉光放电;放电脉冲群的密度和宽度也随气压降低而增加,但脉冲幅值减小。放电的有功功率随气压变化并非单调增减,当放电气压约为0.04 MPa时,消耗的有功功率最小,常压下和近真空时放电的有功功率都要大得多。     

荫罩式等离子体复合放电驱动波形的研究

提出了一种适合三电极荫罩式PDP结构的新型高效复合放电驱动波形.采用二维流体模型研究了三电极荫罩式PDP结构复合放电驱动波形的放电过程,分析了空间电位、壁电荷及带电粒子分布的演变情况.讨论了复合放电驱动波形维持期寻址电极电压对放电特性的影响,计算了维持期真空紫外辐射功耗、放电效率的变化趋势以及电子平均浓度随时间的变化关系,并与传统表面放电驱动波形比较.结果表明复合放电驱动波形在响应频率、放电强度和放电效率等方面均优于传统表面放电驱动波形.     

紫外预电离TEA CO2激光器放电过程的数值模拟

建立了一数值模型模拟紫外预电离TEACO2激光器的放电过程。结合放电电路分析了激光器的动态放电过程,综合考虑了气体放电中所发生的电离、吸附、复合等粒子反应,得到了电子密度、放电电流及放电电压随时间变化的波形,并将模拟结果与实验结果进行了对比。此外,还模拟并分析了放电回路中部分参量对放电特性的影响,获得了有利于激光器稳定放电的条件。     

脉冲参数对指纹放电成像质量的影响

利用介质阻挡放电照相的原理,成功实现了对人体指纹的提取。在静态法提取指纹过程中,记录了在3种脉冲宽度(2ns,3μs,1ms)下放电的指纹图像。放电空间电场分布的分析表明,随着脉冲宽度的增加,正离子在介质层上的累积使得放电空间的电场趋于均匀,导致指纹放电强度在空间的均匀化,从而使指纹成像的分辨率下降。采用较高幅度的ns脉冲放电时,发现了指纹放电中存在丝状放电的痕迹。进一步的实验表明,即使在放电空间不存在介质时,也能观测到良好质量的指纹放电图像。研究结果表明,采用较小幅度的ns脉冲放电技术,不仅提高了指纹图像的清晰度,而且也实现了大气中的辉光放电。     

无声放电CO_2激光器放电参量计算

本文引入了若干无声放电的重要参量,导出了无声放电参量的计算公式,并对研制的 CO_2无声放电激光器的放电实验结果进行了分析计算。证明文中所述 SD 参量计算公式可作为定量分析无声放电的依据。     

激光诱导微弧放电对45#钢的表面强化

使用激光诱导微弧放电的方法对45#钢进行了表面强化.通过实验对比了高压诱导放电(HVGD)和激光诱导放电(LGD)两种表面强化方法.发现激光诱导放电使电极间隙的击穿电压降低了一个数量级,同时放电点和激光焦点重合,实现了对放电点位置的控制.在两种诱导放电过程中放电点的膨胀速度基本相同,但是受到初始放电点大小的影响,激光诱导放电点直径大于高压诱导放电点.在两种诱导放电过程中强化深度都存在最大值,约为180 μm.放电点的强化层山熔凝层和相变硬化层组成,其中熔凝层的硬度最高达到800 HV.     

S.A.W. bandpass filter with ?50 dB sidelobes using unweighted i.d.t.s

The use of a resonantly loaded i.d.t. (r.l.i.d.t.) as an s.a.w. track changer in bandpass filter design is described. A filter with 3dB fractional bandwidth (f.b.w.) of 11.5% and ?50 dB sidelobes is realised using unweighted input/output i.d.t.s of 5? finger pairs each and a 7? finger pair r.l.i.d.t. as the s.a.w. track changer. The scheme is expected to be useful in realising low-shape-factor low-sidelobe bandpass filters using relatively short i.d.t.s.     

X-ray metrology for high-k atomic layer deposited HfxZr1−xO2 films

Hafnium-based dielectrics are the most promising material for SiO₂ replacement in future nodes of CMOS technology. While devices that utilize HfO₂ gate dielectrics suffer from lower carrier mobility and degraded reliability, our group has recently reported improved device characteristics with a modified Hf_xZr_1−xO₂ [R.I. Hegde, D.H. Triyoso, P.J. Tobin, S. Kalpat, M.E. Ramon, H.-H. Tseng, J.K. Schaeffer, E. Luckowski, W.J. Taylor, C.C. Capasso, D.C. Gilmer, M. Moosa, A. Haggag, M. Raymond, D. Roan, J. Nguyen, L.B. La, E. Hebert, R. Cotton, X.-D. Wang, S. Zollner, R. Gregory, D. Werho, R.S. Rai, L. Fonseca, M. Stoker, C. Tracy, B.W. Chan, Y.H. Chiu, B.E. White, Jr., in: Technical Digest - International Electron Devices Meet, vol. 39, 2005, D.H. Triyoso, R.I. Hegde, J.K. Schaeffer, D. Roan, P.J. Tobin, S.B. Samavedam, B.E. White, Jr., R. Gregory, X.-D. Wang, Appl. Phys. Lett. 88 (2006) 222901]. These results have lead to evaluation of X-ray reflectivity (XRR) for monitoring high-k film thickness and control of Zr addition to HfO₂ using measured film density. In addition, a combination of XRR and spectroscopic ellipsometry (SE) is shown to be a fast and non-intrusive method to monitor thickness of interfacial layer between high-k and the Si substrate.     

BOOK REVIEWS AND NOTES

Book reviewed in this article:
E mployee P ublications . By William C. Halley.
E ffective C ommunication in C ompany P ublications . By C. J. Dover.
B riefing and C onference T echniques . By Glenn M. Loney.
T he L anguage of P sychology . By George Mandler and William Kessen.
T he B ases of S peech . (Third Edition.) By Giles Wilkeson Gray and Claude Merton Wise.
R oots for a N ew R hetoric . By Daniel Fogarty, S.J.
W ords and T hings . By Roger Brown.
P utting W ords in T heir P laces . By Doris B. Garey.
O ur L anguage and O ur W orld . (Text Edition.) By S. I. Hayakawa. (Editor.)
S tudent and S ociety —R eadings for C ollege E nglish . By George P. Clark and A. Dwight Culler. (Editors.)
C ontroversy : R eadings to S timulate T hought and D iscussion . By Randall W. Hoffman and Robert Plutchik. (Editors.)
C ollege R eading M anual . By Phillip B. Shaw and Agatha Townsend.
S upervisory and E xecutive D evelopment : A M anual for R ole P laying . By Norman R. F. Maier, Allen R. Solem, and Ayesha A. Maier.
C ritical W riting for T he J ournalist . By Roland E. Wolseley.     

Feasibility of using digital filters to interconnect p.c.m. and f.d.m. transmission systems

A time-division multiplex (t.d.m.) and a frequency-division multiple (f.d.m.) system may be interconnected by means of gates and lowpass filters. The use of digital filters (d.f.s) for this purpose appears attractive when the t.d.m. system uses pulse-code modulation (p.c.m.), because digital-analogue and analogue-digital conversion are unnecessary at the interface between the d.f. and the p.c.m. system. The problems involved in applying d.f.s in this application are discussed. It is concluded that the interconnection of p.c.m. systems with f.d.m. systems using quite low carrier frequencies requires the development of digital circuits operating at several hundred megahertz.     

Enhancement-mode GaAs m.o.s.f.e.t. on semi-insulating substrate using a self-aligned gate technique

A self-aligned gate notched channel GaAs m.o.s.f.e.t. structure on semi-insulating substrate is presented. Device operation is mainly in enhancement mode. The transconductance is comparable to enhancement-mode m.e.s.f.e.t.s, j.f.e.t.s and s.i.g.f.e.t.s; however, the output-current capability is essentially increased.     

BOOK REVIEWS

Book reviewed in this articles:
L anguage , T hought, and C ulture . Edited by Paul Henle.
E nter : the C omics . Translated and edited by E. Wiese.
I ntroductory L anguage E ssays . Edited by Dudley W. Bailey of the University of Nebraska.
C lassics in S emantics . By Donald E. Hayden and E. P. Alworth.
I ntroductory R eadings on L anguage (revised edition). Wallace L. Anderson and Norman C. Stageberg, of the State College of Iowa.
E conomic K knowledge and C omprehension in a N etherlands F arming C ommunity . By H. H. Felstehausen
T eaching E nglish as a S econd L anguage . By Harold B. Allen.
W orking W ith the L atin A merican P ress . By James W. Carty, Jr.
C ourse in G eneral L inguistics . By Ferdinand de Saussure
T he I nternational H andbook of G roup P sychotherapy . Edited by J. L. Moreno.
F ive I naugural L ectures . Edited by P. D. Strevens.     

Reply to 'Comment on "Enlarged cells for the conformal FDTD method to avoid the time step reduction"'

For original article by T. Xiao and Q.H. Liu see ibid., vol.14, no.12, p.551-3, Dec. 2004. For comments by R. Schuhmann, I.A. Zagorodnov and T. Weiland see ibid., vol.16, no.1, p.55, Jan. 2006.     

BOOK REVIEWS

Book reviewed in this articles: Principles of Rhetoric . By Richard E. Hughes and P. Albert Duhamel. The Complete Stylist . By Sheridan Baker. The Writer's Manual : The Grammar and Mechanics of the English Language . By Archibald Jordan. Language , Rhetoric, and Style . By Phillip Damon, John Espey, and Frederick Mulhauser. Writing By Patterns . By Helen E. Lefevre and Carl A. Lefevre. Public Speaking . By George W. Fluharty and Harold R. Ross. You Don't Say : Studies of Modern American Inhibitions . By Benjamin DeMott. The Ill -Spoken Word : The Decline of Speech in America . By Leonard A. Stevens with an introduction by Ralph G. Nichols. Public Speaking : A Rhetorical Perspective . By Jane Blankenship of Mount Holyoke College The Art of successful Communication : Business and Personal Achievement Through Written Communication . By Norman G. Shidle. This Is Reading . By Frank G. Jennings. Perspectives on persuasion . By Wallace C. Fotheringham. Perspectives on Argumentation . Edited by Gerald R. Miller The Mass Media and Modern Society . By Theodore Peterson and Jay W. Jensen, of the University of Illinois, and William L. Rivers, of Stanford University. Personal and Organizational Change Through Group Methods : The Laboratory Approach . By Edgar H. Schein and Warren G. Bennis. Group Problem -Solving Through Discussion . By William S. Smith Report Writing (fourth edition). By Harold F. Graves and Lyne S. S. Hoffman. Report Writing for Business (revised edition). By Raymond V. Lesikar. Communication in the Business Organization . By William Scholz The Penguin Dictionary of English . Compiled by G. N. Garmonsway with Jacqueline Simpson. Clinical Aspects of Remedial Reading . By Clifford J. Kolson, State University College in Potsdam, New York, and George Kaluger, Shippensburg State College in Pennsylvania. Culture in American Education . By Ruth Landes. Freedom and Communications . By Dan Lacy. Introduction to the Field of Speech . Ronald F. Reid Contemporary Controversy : Readings for Composition and Discussion . By Morris Freedman and Paul B. Davis Speech Preparation Sourcebook . By Robert T. Oliver, Carroll C. Arnold, and Eugene E. White, Pennsylvania State University. The Conduct of Inquiry . By Abraham Kaplan. Signal Detection and Recognition by Human Observers . Contemporary readings edited by John A. Swets. Character and Crisis : A Contemporary Reader . Edited by Philip Levine, of Fresno State College, and Henri Coulette, of California State College at Los Angeles. Written Communications for Business Administrators . By Robert D. Hay.     

GaAs power f.e.t.s with semi-insulated gates

GaAs semi-insulated-gate f.e.t.s (s.i.g.f.e.t.s) have been fabricated by Ar+ bombardment in the gate region. The d c. characteristics and microwave performance are compared with those of conventional power m.e.s.f.e.t.s fabricated from the same slice. Up to 2.9W output power with 4dB gain has been obtained from s.i.g.f.e.t. devices at 8 GHz.     

Some results for an r.f.- and p.l.-modulated incoherent carrier

Possibilities of using incoherent carriers, amplitude-modulated by the message-modulated p.f.m., r.f.m. and p.l.m. have been investigated. It has been shown that, for noise bandwidths much smaller than the transmission bandwidth, efficient communication is possible, and s.n.r.s of 50?60dB are obtained for practical p.f.m.-a.m. and r.f.m.-a.m. systems. Some comparisons are also given.