50瓦铜蒸气激光器放电管设计

激光放电管是铜蒸气激光器的关键部件,激光放电管的设计优劣直接影响着铜蒸气激光器的研制。本文主要描述了50瓦铜蒸气激光器激光放电管的设计过程,对放电管的绝热层进行了热计算,结合实际情况得到了结构参数。对放电管的真空密封、缓冲气体循环系统、水冷套等部件进行了设计,给出了各部件的具体结构形式。用该激光放电管进行实验研究,振荡级功率稳定在36瓦以上,用作放大级时平均提取功率达到了52瓦。     

溴化亚铜激光放电管径向声波共振现象研究

为解决大功率溴化亚铜激光放电管中声共振造成的输出功率不稳定问题,通过数值分析的方法给出了溴化亚铜激光放电管内径向声波振动的数学模型,并获得了激光放电管内声波径向驻波分布的解析表达式,分析了放电频率与激光管固有频率的关系,明确了声共振是导致激光介质重新分布并对输出功率产生影响的原因.由此得出结论:寻求一个在声共振本征基频附近的放电频率,并且能够使激光器稳定工作,是提高激光输出功率及提高激光器效率的一种有效手段.     

以石墨片改善氩激光器的性能

石英放电管中的耐热石墨隧道能使室温氩离子激光实验装置在无水冷的情况下运转。现有的氩激光器商品使用了庞大的水冷系统,以使放电管不致在蓝-绿激光所产生的1,000 ℃温度下熔化。     

Sr+复合激光放电管气体温度场与输出功率的限制

为了使输出波长为430.5 nm的Sr 复合激光能达到实际应用的水平,对Sr 复合激光放电管温度场进行了分析;利用热流耗散泊松方程,给出Sr 复合激光放电管内温度场分布的数学模型,获得了Sr 复合激光放电管气体温度场径向分布的解析表达式,明确了温度分布与输入电功率及缓冲气体热传导系数之间的关系,分析了温度分布与输出功率的关系。指出径向温度分布不均匀是导致输出功率受限的主要原因。其结果与实验一致,对该类激光器的实用化研究提供了富有启发性的理论分析。     

激光陀螺中朗缪尔流形的研究

为了减小激光陀螺中朗缪尔流导致的误差,研究了在阴、阳极之间增加旁路管对放电管朗缪尔流的控制作用。采用气体辉光放电理论,通过改变旁路管半径、放电电流和气体压强,计算了多种情况下放电管的朗缪尔流形。结果表明,上述3个参量的改变都会导致朗缪尔流形的改变,更为重要的是,完全可以将放电管中基模截面上的平均朗缪尔流速调整为0。该发现很好地解释了激光陀螺相关研究中未能解释的一些实验现象,对减小激光陀螺中朗缪尔流零漂从而进一步降低激光陀螺的温度敏感性具有一定的意义。     

河北大学研制成功“无水冷CO2激光器”

河北大学物理系采用环状石墨散热片代替水冷放电管，设计制作成功无水冷CO2激光器。激光器腔长28cm，放电管长20cm．内径4．3mm，最佳工作电流8mA左右．获得稳定激光输出5W．妊犬输出功率可达7W以上。     

扁平放电管He-Ne激光器

为了获得短腔大功率的He-Ne激光输出,本文提出了一种新型He-Ne激光器,采用扁平形放电管,以便增加横向尺寸提高功率。文中讨论了该激光器的设计原理以及实验结果,包括工作总气压、He与Ne的气压比、放电电流等对激光输出功率的影响,还介绍了该种放电管结     

鳃、钙离子复合激光激励电路的分析

对Sr^ 、Ca^ 复合激光所用的Blumlein电路的放电过程和脉冲波形进行了计算机模型。在相同电路参数时,经模拟得到的放电管电流脉冲波形和实测的波形相一致。给出了该电路中各元件上放电脉冲波形间的时间关系,明确了放电过程的先后次序以及对应放电管的击穿电压和时刻。计算和比较了不同电路参数组合时流过放电管的电流脉冲波形,按照复合激光对放电电流脉冲后沿的要求,获得了一组较佳的电路参数。     

放电管温度效应与He-Ca+复合激光功率输出分析

为使输出波长为373.7/370.6 nm的ca+复合激光能达到实际应用的水平,对Ca+复合激光放电管温度场进行了分析,通过求解热流耗散泊松方程,获得了Ca+复合激光放电管气体温度场径向分布的解析表达式,明确了温度分布与输入电功率及缓冲气体热传导系数之间的关系,分析了放电管温度场分布与输出功率的关系,指出径向温度分布不均匀是导致输出功率受限的主要原因之一,其结果与实验一致,为该类激光器的实用化研究提供了理论分析结论.     

氧化铍-金属结构氩离子激光器

本文介绍了氧化铍放电管的特点,描述了一种氧化铍—金属结构氩离子激光器的基本构造。在内径3.8毫米、长36厘米的氧化铍放电管氩离子激光器中,在40安培电流下获得了0.86瓦的激光输出。     

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.     

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.     

REVIEWS

Book reviewed in this article:
power of words . By Stuart Chase.
understanding grammar . By Paul Roberts.
essays on thinxing and writing . By W. Paul Jones.
current trends in information theory . By Brockway McMillan and others.
communciation and persuasion: psychological studies of opinion change . By Carl I. Hovland, Irving L. Janis, and Harold H. Kelley.
annual review of psychology . Edited by Calvin P. Stone and Quinn McNemar.
the living brain . By W. Grey Walter.     

Book Reviews

Book reviewed in this article:
Power—and the Courage to be Free by Hanno Hardt
Cable Television and the FCC: A Crisis in Media Control by Don R. LeDuc.
The Media in America by John Tebbel.
Popular Images of Politics by Dan D. Nimmo.
The Study of Social Dialects in American English by Walt Wolfram and Ralph W. Fasold.
Gaming: The Future's Language by Richard Duke.
Auding and Reading: A Development Model by Thomas G. Sticht, Lawrence J. Beck, Robert N. Hauke, Glenn M. Kleiman, and James H. James.
Radio and Television Broadcasting in Eastern Europe by Burton Paulu.
Paralanguage and Kinesics by Mary Ritchie Key.
Sociolinguistics: A Crossdisciplinary Perspective edited by Roger W. Shuy.
The Mass Media: Aspects of Modern Sociology by Peter Golding.
Human Communication Handbook: Simulations and Games by Brent D. Ruben and Richard W. Budd.
Vienna Broadcasts to Slooakia 1938–1939: A Case Study in Subversion by Henry Delfiner.
Teaching Reading in the Secondary School by Wilma H. Miller.
Mass Media in America by Don R. Pember.
Communication and Behavior edited by Gerhard J. Hanneman and William J. McEwen.
Film Language: A Semiotics of the Cinema by Christian Metz. Translated by Michael Taylor.
Communication Behavior and Experiments: A Scientific Approach by R. Wayne Pace, Robert R. Boren, and Brent D. Peterson.
How Adults Learn by J. R. Kidd.
How to Read Donald Duck: Imperialist Ideology in the Disney Comic by Ariel Dorfman and Armand Mattelart. Translation from the Spanish version, first published in 1971, and introduction by David Kunzle.     

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.     

C.C.D./C.M.O.S. transversal filter using switched-capacitor technique for signal detection

A fully integrated c.c.d. filter has been built with a low power consumption. The c.c.d. filter employs c.m.o.s. support circuits and switched-capacitor techniques for signal detection. The power consumption of the filter is 20 mW.