OS IO -L—C > WAS f.AG/B-2X: Tf-04 ey ECNBriels National Aeronautics and Space Administration Electronic Components and Circuits Electronic Systems Physical Sciences Materials Computer Programs Mechanics Machinery Fabrication Technology Mathematics and Information Scierices DSAODdROO GY” Life Sciences COMPLETED N f GG ANLIPZ Sm=I" ES April 1998 SNN INTRODUCTION Tech Briefs are short announcements of new technology derived from the research and development activities of the National Aeronautics and Space Administration. These Bnefs ernphasize information considered likely to be transferable across industrial, regional, or disciplinary lines and are issued to Availability of NASA Tech Briefs and TSP’s Distribution of NASA Tech Briefs, a monthly periodical publication, is limited to engineers in U.S. industry and to other domestic technology transfer agents. 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Stennis Space Center Technology Utilization Officer Technology Utilization Officer Technology Utilization Officer Technology Utilization Officer Mail Code 223-3 Mail Stop PT-PMO-A Mail Stop 156-211 Code HA-30 Moffett Field, CA 94035 Kennedy Space Center, FL 32899 4800 Oak Grove Drive Stennis Space Center, MS 39529 Pasadena, CA 91109 Patent Counse! Patent Counse/ Mail Code 200-11 Mail Code PT-PAT Moffett Field. CA 94035 KennSpeaced Cyente r, FL 32899 NASA Headquarters Goddard Space Flight Center Research Center NASA Resident Office-JPL Technology Utilaation Officer Technology Utilization Officer Technology Utilization Officer Technology Utilization Officer Code OU Mail Code 702-1 Mail Stop 143 Mail Stop 180-80! Washington, DC 20546 Greenbelt, MD 20,7! Hampton, VA 23665 4800 Oak Grove Drive Pasadena, CA 91109 Assistant Genera! Patent Counsel Patent Counse! Counsel for Patent Matters Mail Code 204 Mail Code 279 Patex tC ounsel Code GP Greenbelt, MD 20771 Hampton, VA 23665 Mail '‘Sode 180-801 Washington, OC 20546 4807) Oak Grove Drive Pasadena, CA 91109 Lyndon B. Johnson Space Lewis Research Center George C. Marshal! Space Dryden Flight Research Center Technology Utilization Officer f Center Center Technology Utilization Officer Mail Stop 7-3 Technology Utilization Officer Techr logy Utilization Officer Mail Code IC-4 21000 Brookpark Road Code ATO' M/S 021-31 Houston, TX 77058 Qreveland, OH 44135 Marshall Space Fight Center Bidg. 4832 Whse 7 Al 35612 Lilly Dr Patent Counse/ Patent Counse! Edwards, CA 93523 Mail Code AL3 Mail Code LE-LAW Patent Counse! Houston, TX 77058 21000 Brookpark Road Mail Code 0001 Cleveland, OM 44125 Marshall Space Fight Center Al. 35812 NASA Tech Bnets, Apri 1998 LARIN PACE NASA Tech Bnefs. Apri 1998 & TechBriefs “2 5 Electronic Components and Circuits 15 Electronic Systems 23 Physical Sciences 37 Materials 43 Computer Programs 47 Mechanics 51 Machinery 8U8 @9dO 6 55 Mathematics and Information Sciences This document was prepared under the sponsorship of the National Aeronautics and Space Admunistration. Neither the United States Government nor any person acting on behalf of the United States Government assumes any liability resulting from the use of the information contained in this document, or warrants that such use will be free from privately owner! nghts NASA Tech Bnets, Apri 1998 3 LAIN PAE Electronic Components and Circuits Hardware, Techniques, and Processes Computation of Characteristics of a Helical TWT Silow-Wave Circuit 8 Line-Focus Photovoltaic Module With Solid Secondary Optics 10 Pulse shepherding im Nonbnear Fiber Optics 11 Discnmuinator-Stabilized Superconductive/Ferroelectric Oscillator 12 Glove Senses Angies of Finger Jouns 12 Computing Limiting Voltages vs. Temperatures for Ni/Cd Cell: NASA Tech Bnefs, Apri 1998 é BLARI PARE Computation of Characteristics of a Helical TWT Slow-Wave Circuit Accurate numerical simulation can be substituted for Lewis Research Center. experimentation to reduce the cost of development. Cleveland, Ohio" A computational study has been per- formed to show that one can accurately compute the cold-test electromagnetic Charactenstics of the helical slow-wave Circuit of a traveling-wave tube (TWT) Previous efforts to apply computer-aided design techtno hieliqcal uTWeT csrou its nad mvolved computer Codes based partly on simpiitying approximations of TWT geoams theey retlate nto eelectrsomag net Cc Charactenstics: Nelces have Deen approas~ shweathms, aneltx teapeds na ve been approaws mhavaingt 2eer0 dthi ck. nesses, and Gelectnc rods that support the nehoes have been approsemabtyi ceomdb : natons of homogeneaondu insholmoyge - HELICAL SLOW-WAVE STRUCTURE (BARREL OMITTED FOR CLARITY) neously loaded volumes with effective penntHowtevevr, itot simeulatse e.lect ro- magnetic charactenstcs accurately, one must use @ computer Code thal represents the geometry of the TWT in its three-dimen- sional complexity. Thess can be done by use of the computer program MAFIA (Solution of Maxwells Equations by the Finite InteAiggonrtn)a —t a ipoweortun, m od- viar electromagnetic-simulation code wriitn tFOReTRnAN 77 for use in the com- puter-aded design and analyss of two- and three-dimensional electromagnetic Cy Cavites, waveguiandd eansten.na s in MAFIA, the geometnc accuracy is limited only by the resolution of the com- putational gnd used to represent the geoomf thee motdelred ydev ice. The fintte imtegration technique (FIT) algorithm impie- mented in MAFIA yeids a matnx of finte- Gifference equations for the elecinc and HELICAL SLOW-WAVE STRUCTURE IN COMPUTATION-AGRLID REPRESENTATION magnetic fields in the device under study Solutions can be obtained in the time or Figure |. Three Turns of thy: Helical TWT Siow-Wave Circuit are depicted here by a plot trom the frequency domain. or in the static MAFIA, wherein the helix is generated in a cylindncal coordinate system by varying aa! and Gomwheare iapplnicab le azimuthal coordinates consistently with the formula for a circular helix For clatrhei batrrye! ,su r- in the study, MAFIA was applietod a rounding ihe dielectnc rods is omitted from ths view TWT slow-wave Structure that included a copper-plated rectangular tape wound ance, and radio-frequency (RF) losses standing waves with an integral number into a helix, whch was Supported by rec The computational approach to deter. of half wavelengths in the circu't section tangular BeO Gielectnc rods inside a con muning the dispersion characteristics thus isolated Guctive barrel (see Figure 1). The electncal involved the use of boundary Conditions The interaction impedance is computed resistivittes of the Nelx and barrel, the anatlo thoose gusedo inu tr >s exp eri- Grectly by calculating the magnitude of the width, thecankd nheliecals pitsch ,of t he mental approach: in the experimental space harmonic componof ethen lton g: tape, and the Gelectnc properties aid approach, one determines the disper- tudinal electric fieid with whch the electron Gimeof nthe srodis woere nall sinco rpo sion charactenstics from measurement beam iS synchronous, and the total AF rated into the MAFIA model of resonant frequencies of a section of power flow. Because the interaction The TWT coks-test characteristics of the slow-wave circuit shorted at both impceannodt bae mneasucred eGirec tly, primary interest are the slow-wavdeis - longitudinal ends. in the computational the experaipprmoaceh ninvtolvaes lme a- persion (normalized phase velocity vs approach, a MAFIA helix model is trun- sunng resonant frequeinn ac peirteursbe d frequency), the on-axis electron- cated with either electric or magnetic resonant Circull and Genving an expression bearn/siow-wave interaction imped- waits at two end points to simulate relating the change in resonant frequen. NASA Tech Brets, April 19¢8 ta’ procedure less acourale tan Grect computawitthi MoAFnI A The compuotf RaF ltossies omvnoiv es consiodf tehe reffaectts oif fointen co r. Gucof hte helta anyc ba rre! anodf t he a loss tangent of the Gielectic (taken to be 0.00to0r 6BeO ) In the stutdhey ef.fe ct of surtace rougness ™ moreasirtgh e eflective resistivity of the tape was also PViNtehyta oosre rmakzed takwttoe acncoun t. The total RF loss was calculated as a sum of Surtace resistivity and Gwelectnc losses and summmarvedn m terms of attenpeur aturtn oif tohen he lx« @S a tuncotf fireoquennc y Figure 2 shows principal electromag: netic parameters of the slow-wave Struc- ture, both as compbuy tMAFeIAd a nd aS Geterruned expermentally The excel- lent agreement between computational and experimental results Gemonstrates the utiity of numencal sinulatiaosn a Substitute for building and testing TWTs to analyze numerous alternative TWT Jesigns. in compawritih esxpoenmnen - tation, numencal simulation costs less and takes less time, and thereby also aftords additional treedom to analyze both novel designs and small variations On previous designs. This work was Gone by Caro! L. Kory of Anaiex Corp. for Lewis Research oO Center further informias tcointoainne d 10 1§ ina TSP [see page 1] FrequencyG,H z inquines concerning nights for the commusee ofr thics iniventaion lsho uld Figure 2 Three Parameters of Major interest for characterizing the performance of the siow- be addrto eNASAs Lsewise Redsear ch wave structure depicted in Figure | were computed by MAFIA and measured Center, Commercial Technology Office, Attn: Tech Bnet Patent Status, Mail Stop oes between the perturbed and unper. ance Ths denvation necessitates several 7-3, 21000 BrookpaRroakd , Cleveland, turbed circuits to the mteraction mped- approxiremndaenntg ithoe enxpsenm,en - Ohio 44135. Refteo rLEW -16571 Line-Focus Photovoltaic Module With Solid Secondary Optics Cell design and optical and electrical configurations Lewis Research Center, are combined to obtain high efficiency. Cleveland, Ohio The figure @ustrates aspects of a light- tons are combined to obtain high energy- rectanguar entrance and ext apertures weight, relatively nexpensive solar photo- conversion efficiency. in additithoe inno,or - with parabolic side walls, on whch inodent voltaic module suitable for use on Earth or poration of the secondary sold optics ight is totally internally reflected The para- i Outer space in conunction with at least a increases rewstance to ionizing radiation meters of the parabolas are chosen in cor. singie-axs Sun-tracking apparatus. The Each tine-focus icyindnFrcesnaell l)en s junction with the length and width of the module Contains line-focus primary Fresnel compnses a thin, arched glass superstrate tandem cel par to maanuwze the concen lenses that act in conuncwith osnpot . Set that protects and supports a silicone tration of ight onto the calls over suitable focus, compound parabolic secondary rubber sheet, into which Fresnel-lens acoaandp Sunt-poiantinng-ercror eang ies sokd optics to concentnordeantt seu grooves have been mokied. A spot-foous Taking advantage of the rectanguiartyo f light onto tandem, pared GaAs and GaSb secondary sold optic is adhesively bonded the entrance aperture. each secondary photocallvs aorraylsd taloang ithec foc al to the input face of each tandem aptic Can be butted up against the adjacent ines. The tandem-hotovoltac-cdeeslilgn GaAs/GaSb cel pair Each secondary secondary apticis) to maenize utilization of and the optical and @ectrical configura optic, molded in siioone rubber, features the ight focused by the Fresne! jens NASA Tech Brets, Apri 1998 FRESNEL LENS AND CELLS ALONG ONE FOCAL LINE Fresnei Lenses and Secondary Optics are used together to concentrate light more effectively than could be done using either type of optic alone The overall design affords enhanced energy-conveerfsfiicioennc y The tandem pairs of cells are designed the focal line, while the GaAs cells in each module amounted to an average power of to enhance energy-converefsfiicioennc y triplet are Connecint peardali el Thus. the 261 W per cel — corresponding to an by exploiting diffenng spectra’ sensitivites vORage of the tiplet senes of GaSb cells overall energy conversion efficiency of 23.3 The top (GaAs) cel in each par 6 sens matchetsh e votiage of the GaAs cells perceinn cotntr.ast , the energy-conversion te to the visible portion of suniignt and maing @ possible to Connect both tnpiets effoofe relantivecly eexpsensi ve. Tagile allows the intrared portion to pass through ) Daralel Al of the senes/paralie! con large-area arrays of fat S and GaAs oelis to the bottorn (GaSb) cell, which is sens: nected tnplets along the focal ine can then nave generally been less than 20 percent tive to intraed The energy-comsieo n be strung together in sentoe osbta in a Ths work was done by Lews VM Fraas efficiency of the GaAs cell is 24 penvent, hugher output voltage and Janes E. Auoef JrX Oyrysta ls, inc. wile that of the GaSb cel is 6 per ent The cells are mounted on ceramic sub- and Mark J O'Nofe Entiechl, i nc., for thus. the energy-conversion efficiency of Strates (ormnitted from the figure for clarity) Lewis Research Center further nfo the tandem cell par is 30 percent The senes and parallel electrical comm. matis ciontoainend i na TSP Isee page1 ) The terminaofl sth e tandem cells in tions are formed in metal patterns on the inquiries concerning nights for the each par are arranged perpendicularlyt o substrates. Gectahe suerises ceonn ec commusee ofr thisc invientaion lsho uld each other Tandepmainrs -arce gerolupe d tons are made over short distances along be adoresse.J to NASA Lewis Research together in threes along each focal tine, by the foca6:S . the overall senes electrical Center, Commercial Technology Office, use of a voliage natchng combinationo f resis(Sts realatnrvecty el ow Attn: Tech Bnet Patent Status, Mail Stop senes and parallel elecincal connections A prototype module contain2i4n tga n 7-3, 21000 BrookpaRrokad , Cleveland Each GaSb cel generonae-tttwed st he Gerr)-cel pars was Construacndt teesdte d Onno 44135. Retert o LEW. 16385 volotf aa GgaAse c el The GaSb calls n under orm dated surbg’t in the absence of each tnipiet are cory rected in senes along the atmosphere. The overal output of the NASA Tech Brets, Apri 1908