电子回旋脉射之非稳态与浑沌行为

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1、電子迴旋脈射之非穩態與渾沌行為NonstationaryandChaoticBehavioroftheElectronCyclotronMaserT.H.Chang(張存續)Dept.ofPhysics,NationalTsingHuaUniversity,Hsinchu,Taiwan4/15/2005@NCHU1TheMotionofChargedParticlesinMagneticFieldsTheperiodandfrequencyofthechargedparticleare2πr2πmm2πT===vqBqB1qBqBfc===T2πm

2、m2πThefrequencyiscalledthecyclotronfrequency.Allparticleswiththesamecharge-to-massratio,q/m,havethesameperiodandcyclotronfrequency.(Non-relativisticlimit)2TheCyclotronAcceleratorTheoperationofthecyclotronisbasedonthefactthattheorbitalperiodofaparticleinamagneticfieldisindependentofitsspee

3、d.ElectronCyclotronResonance(ECR)employsthisfeaturetogeneratehighdensityplasma.Canwefindtheinverseeffectthatconvertsthekineticenergyofthechargedparticlesintoacpower(waveenergy)?Yes!3PhysicalConditionRequiredfortheGenerationofCoherentRadiation1.AmechanismfortheRFfieldstobunch(群聚)aDCelectron

4、beamintoanACelectronbeam.2.Synchronism(同步)betweenthebunchedelectronsandtheRFfields.4PrincipleoftheElectronCyclotronMaser-arelativisticbunchingmechanismeBrateofdoingworkΩc=byexternalfieldsγmvvvqv⋅EE=Eoxˆcos(ωt)ω−Ωc≥05SignificanceoftheECM---ToFilltheTerahertzGaponephotonmultiple-photonmultip

5、lephotonperexcitation,perelectron,perelectron,largeinteractionlargeinteractioninteractionspacespacespace~wavelength↓↓↓67AUniqueFeatureoftheGyro-BWO---NonlinearFieldContractiongyro-BWO(internalfeedback)e)nonlinearfieldd6tuIb=5.0Acontractionli4pbackward-waveω0.80Aam2interactionld0.06Aefi(rel

6、ativescale005101520ion)10Ib=5.0Aitω=kzvz+Ωcs50.80ATE11o0.06Apkze0dy-5gshortenedfeedbackloop(relativescale-10ener05101520Z(cm)8ECMbasedDevices---gyrotronsThegyrotronisacoherentradiationsourcebasedontheelectroncyclotronmaserinteractiongyro-monotronhighaveragepowergyro-BWOcontinuousfrequencyt

7、unability(relativelyunexploited)Inherentlyahighpowersource,thegyrotronissusceptibletoavarietyofsingle-andmulti-modenonstationarybehavior910Characteristicofgyro-monotron(reflectivefeedback)ωTE11forward-waveω=kzvz+Ωcinteractionkz10cm3.175mm2.66mm3.175mmbackwardw