Millimeter-Wave Gyrotron Traveling-Wave Tube Amplifiers

200 Pages·2014·9.03 MB·English

by  Chao-Hai Du

Chao-Hai Du · Pu-Kun Liu
Millimeter-
Wave Gyrotron
Traveling-Wave
Tube Amplifi ers
Millimeter-Wave Gyrotron Traveling-Wave Tube
Amplifiers

Chao-Hai Du • Pu-Kun Liu
Millimeter-Wave Gyrotron
Traveling-Wave Tube
Amplifiers
123
Chao-HaiDu
Pu-KunLiu
SchoolofElectronicsEngineering
andComputerScience
PekingUniversity
Beijing,China
ISBN978-3-642-54727-0 ISBN978-3-642-54728-7(eBook)
DOI10.1007/978-3-642-54728-7
SpringerHeidelbergNewYorkDordrechtLondon
LibraryofCongressControlNumber:2014940850
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Preface
Agyrotrontraveling-wavetube(gyro-TWT)amplifieriscapableofgeneratinghigh-
powerandbroadbandcoherentelectromagneticradiationonthelevelofhundredsof
kilowatts in the millimeter-wave range. It is one of the most promising candidates
of the electromagnetic-wave power amplifier for the next generation of imaging
radars and long-range high-data-rate wireless communications. It would play an
important role in many fields, such as national security, small objects tracking in
the outer space, accurate atmosphere and weather monitoring, and so on. A gyro-
TWT amplifies the driving power based on the convective instability principle of
the relativistic electron cyclotron maser (ECM). The amplification simultaneously
suffersfromcompetingabsoluteinstabilities,whichleadtocomplicatedself-excited
oscillations.Asaresult,theinstabilitycompetitionnotonlystopsthesystemfrom
efficientoperationbutalsohinderspracticalapplications.Investigatingthephysics
oftheinstabilitycompetitionandexploringsolutionstosuppressself-excitedoscil-
lationsturnintoprimaryfactorsessentiallyrelatedtothegyro-TWTdevelopment.
Hence, it is of important academic value and engineering application to study the
beam-waveinteractionmechanismandtorevealtheinstabilitycompetitionphysics
in depth, as a way to further enhance the amplifier performance and promote its
applicationinhigh-powermillimeter-waveradarsandcommunicationsystems.
This book focuses on the beam-wave interaction mechanisms and the compe-
tition relations between the convective instability and the absolute instability in
gyro-TWT amplifiers. The book starts with a technical review of the gyro-TWT
development in past decades in Chap. 1. Chapter 2 presents a comprehensive
presentation of the linear theory and nonlinear theory of ECM interaction. The
main content of the book is conveyed in Chaps. 3, 4, and 5, including detailed
investigation of the lossy dielectric-loaded (DL) waveguide, ultrahigh gain gyro-
TWT amplifier, and lossy DL gyro-TWT amplifier. Chapter 6 is arranged as an
exploratorysection.Threenovelconceptsrelatedtoamplifierinteractioncircuitare
introducedhere.Chapter7presentssomekeytechnologiesrelatedtodevelopinga
gyrotronamplifier.
Thecontentsofthebookoriginatefromrecentyearstheoreticalandengineering
works on developing gyrotron amplifiers in our group. We try to present them in
v
vi Preface
a comprehensive way, especially a lot of vivid figures are conceived to illustrate
the complicated physics. The millimeter-wave gyrotron amplifier has experienced
a tremendous advance in the past decade. We hope this book would be helpful to
promoteitsfurtherdevelopment.
Beijing,China Chao-HaiDu
Pu-KunLiu
Contents
1 ReviewofGyrotronTraveling-WaveTubeAmplifiers................... 1
1.1 MicrowaveElectronics.................................................. 1
1.2 ElectronsCyclotronMaserandGyrotron.............................. 4
1.2.1 ThePrincipleofECM.......................................... 4
1.2.2 TheCharacteristicsofaGyrotron.............................. 6
1.2.3 TheCategoryofGyrotronTubes............................... 7
1.3 GyrotronTraveling-Wave-TubeAmplifiers............................ 10
1.3.1 TheDevelopmentofGyro-TWTs.............................. 10
1.3.2 CommentsonTechnologies.................................... 14
1.3.3 ProblemsandProspects ........................................ 19
References..................................................................... 21
2 FundamentalTheoryoftheElectronCyclotronMaser ................. 27
2.1 Introduction ............................................................. 27
2.2 TheoryoftheWaveguides.............................................. 29
2.2.1 TheoryofUniformDielectric-LoadedWaveguide............ 30
2.2.2 TheoryofPeriodicDielectric-LoadedWaveguide............ 34
2.3 TheoryoftheElectronCyclotronMaserinWaveguideSystem...... 39
2.3.1 PartitioningtheTransversePlaneofanECMSystem ........ 40
2.3.2 TheLinearTheoryofDielectric-LinedECMSystem ........ 42
2.3.3 TheNonlinearTheoryofDielectric-LoadedECMSystem... 45
2.3.4 BasicConcepts.................................................. 47
2.4 Summary ................................................................ 50
Appendix I: Derivation of the Linear Theory
inDielectric-LinedWaveguide......................................... 50
1.TheFieldExpressioninGCC ....................................... 51
2.TheTransversePerturbedBeamCurrent............................ 52
3.TheLaplaceTransformation......................................... 55
References..................................................................... 58
vii
viii Contents
3 Novel Propagation Characteristics of Lossy
Dielectric-LoadedWaveguides ............................................. 61
3.1 Introduction ............................................................. 61
3.2 DielectricLoss-InducedModalTransition............................. 63
3.2.1 EigenvalueandModeIdentification ........................... 63
3.2.2 ModalTransition................................................ 66
3.2.3 ModalDegeneration............................................ 69
3.2.4 ModalSelection................................................. 71
3.3 PeriodicDLWaveguidewithSuppressedPropertyofPeriodicity.... 74
3.3.1 EigenvalueandModeIdentification ........................... 75
3.3.2 InfluenceofDielectricSlotRatio.............................. 75
3.3.3 ModalTransitioninaPeriodicDielectric
WaveguideSystem.............................................. 78
3.3.4 Suppressing the System Periodicity Using
DielectricLoss.................................................. 81
3.4 ModeMapping.......................................................... 82
3.5 Conclusion .............................................................. 87
References..................................................................... 88
4 InstabilityCompetitioninanUltrahighGainGyro-TWTAmplifier.. 91
4.1 Introduction ............................................................. 91
4.1.1 AnalysisMethodoftheInstabilityCompetition .............. 92
4.1.2 TheKeyFactorsofInstabilityCompetition................... 93
4.2 BalanceBetweentheBackwardWaveandForwardWave
inanAbsoluteInstability............................................... 94
4.2.1 InternalFeedbackDynamicsofanAbsoluteInstability...... 96
4.2.2 MagneticTuning................................................ 98
4.2.3 High-OrderAxialMode........................................ 101
4.2.4 WaveguideWallLoss........................................... 104
4.2.5 AMultistageInteractionGyro-TWTCircuit.................. 106
4.3 OscillationwithMulti-steadyStates ................................... 109
4.3.1 Self-ConsistentNonlinearInstabilityStudy................... 109
4.3.2 AttenuationStrengthoftheLossyLinearStage............... 110
4.3.3 Multi-steadyStatesofAbsoluteInstabilityOscillation....... 111
4.3.4 ApplyingMagneticFieldTaperingtoEnhance
NonlinearStageStability....................................... 114
4.3.5 InfluenceoftheDownstreamPortReflection ................. 116
4.3.6 Pre-bunchedECMRadiation................................... 117
4.4 Summary ................................................................ 118
References..................................................................... 119
Contents ix
5 ALossyCeramic-LoadedMillimeter-WaveGyro-TWTAmplifier .... 121
5.1 Introduction ............................................................. 121
5.2 PropagationCharacteristicsApproximation........................... 123
5.2.1 The Propagation Characteristics
oftheDielectric-LoadedWaveguide........................... 123
5.2.2 LinearandNonlinearInstabilityStudy........................ 126
5.3 Linear Study of Full-Wave Interaction
inDielectric-LoadedWaveguide ....................................... 132
5.3.1 LinearInstabilityCompetitionStudy.......................... 133
5.3.2 LinearGrowthRateStudy...................................... 135
5.4 Nonlinear Study of Full-Wave Interaction
inDielectric-LoadedWaveguide ....................................... 137
5.4.1 NonlinearInstabilityCompetitionStudy...................... 138
5.4.2 AmplificationCharacteristics .................................. 140
5.5 Beam-WaveCouplingStrength......................................... 143
5.6 Summary ................................................................ 149
References..................................................................... 149
6 Exploring New Mechanisms for High Power
Millimeter-WaveGyrotronAmplifiers .................................... 151
6.1 Introduction ............................................................. 151
6.2 AnECM-CascadedAmplifier.......................................... 153
6.2.1 TheConceptofECM-CascadedAmplifier.................... 154
6.2.2 Beam-WaveInteractioninanECM-CascadedAmplifier..... 155
6.2.3 Discussion....................................................... 157
6.3 High-OrderModeDriftTube........................................... 158
6.3.1 TheConceptofHigh-OrderModeDriftTube ................ 158
6.3.2 Beam-WaveInteractioninOvermodedDriftTube............ 159
6.3.3 Discussion....................................................... 161
6.4 High-PowerGyrotronAmplifierBasedonBi-modesOperation ..... 161
6.4.1 TheConceptofBi-modesOperation .......................... 161
6.4.2 ThePrincipleofBi-modesOperation.......................... 163
6.5 High-PowerGyrotronAmplifierBasedonECM-Cascade
andPre-bunchingScheme(Gyro-CPA)................................ 164
6.5.1 KeyTechnologiesRelatedtoaGyro-CPA..................... 164
6.5.2 PrincipleofAmplifierBasedonECMCascade
andPre-bunchingExcitation................................... 165
6.5.3 Discussion....................................................... 171
6.6 Conclusion .............................................................. 171
References..................................................................... 172