太赫兹仿真成功案例VORPAL.pdf

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1、VORPALUsedinDesignOptimizationofaMicrofabricatedLadderTWTProblemDescriptionThecommonhelixshapetraveling-wavetube(TWT)presentsproblemsasfrequencyincreasestowardstheTeraHertz(THz)range(necessarytoavoidradiationdamage)becausethedevicebecomessmallermakingitdifficulttomanufacture,diff

2、iculttodissipateheatandfragile.ThemicrofabricatedladdertypeTWTpresentsanidealsolutionduetothefactthatitisasymmetricdevicerequiringfewerpiecesandsimplerassemblysoitcaneasilybefabricatedatlowcost.However,importantfeaturesofaTHzdevicesuchasthis,likenonlineargainandbandwidth,arenotwe

3、llunderstood.SolutionVORPALwasusedbyresearchersattheUniversityofColoradoatColoradoSprings(UCCS)toreliablypredictthebeamopticsbehaviorofamicrofabricatedladdertypeTWTforthefirsttime.Theyextendedthefrequencyrangeuptonear50GHzwheretheconventionaltypeTWTcannolongerbemanufactured.Using

4、VORPAL,theyfoundtheoptimallengthoftheladderaswellastheoptimalpower.The3DVORPALresultswillbeusedtodesignthenewladdertypeTWTatUCCS.WhyVORPAL?ThemicrofabricatedladderTWTisinintricatedevicerequiringmanydifferentphysicsmodelsincludingparticleswhichmoststandardelectromagneticmodelsdon'

5、tinclude.VORPALalsohasaDey-Mittracut-cellalgorithminordertomodelcomplexgeometriesinanonstair-steppedmannerleadingtosmoothsurfacesoverwhichtosolveMaxwell'sequations.Thecomplexityinthephysicsmodeledandthegeometryofthedesignrequired3Dsimulationsutilizingthedistributedparallelcomputi

6、ngcapabilitiesofVORPALtocutdownsimulationtimeto4dayson32cores.“VORPALhasbeeninvaluabletousindesigningourladdertypeTWT,”saidProfessorHeatherSongoftheUniversityofColoradoatColoradoSprings.“Noothercodeavailabletouscouldgivethenonlinearbeamdynamicsofthiskindofdevice.Withoutthedistrib

7、utedcomputingcapabilitiesofVORPAL,theserunswouldhavetakenmonths,makingthemeffectivelyimpossible.Also,theTech-Xsupportstaffwasagreathelpwithsettingupourproblemandgettingustoasolution.”Figure1:VORPALgeometryshowingthe3Dmodeloftheladderstructureinredandthedielectricinblue(left),andt

8、helongitudinalphasespaceplotoftheelectro