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The physical design of cavity and magnetron injection gun (MIG) for a realistic, DEMO-compatible, coaxial-cavity 238 GHz 2 MW CW fusion gyrotron is developed in this work, having auxiliary frequencies at 170 GHz and 204 GHz. Novel systematic approaches towards multi-frequency mode selection, magnet requirements, and MIG design are presented. Mode deterioration and voltage depression variation due to insert misalignment versus cavity wall and/or versus electron beam are studied.
koaxialer Innenleiter --- misalignment --- coaxial insert --- nuclear fusion --- Kernfusiongyrotron --- Versatz --- Mehrfrequenz-Gyrotron --- Gyrotron --- multifrequency gyrotron
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In this work the feasibility of a 4 MW 170 GHz coaxial-cavity gyrotron for continuous wave operation is demonstrated. For the first time complete physical designs of the major gyrotron components are elaborated. In a first step, one possible new operating mode is determined, followed by the development of detailed physical designs of the major gyrotron components: Diode and triode type electron gun, coaxial cavity, two-beam quasi-optical output coupler and depressed collector.
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Gyrotrons are high-power mm-wave tubes. Here, the design, construction and experimental investigation of a 20 kW, 28 GHz gyrotron (2nd harmonic) are reported. This tube was designed to evaluate new emitters for future highly efficient and reliable fusion gyrotrons and for material processing applications. Following experimental results have been achieved in CW operation: 22.5 kW output power at 23.4 kV electron beam voltage and 2.23 A beam current with the world record efficiency of 43 %.
Microwave-Materials-Processing --- Wirkungsgrad --- Efficiency --- Kernfusion --- Emitter-Technologien --- Nuclear-Fusion --- Emitter-Technologies --- Gyrotron --- MikrowellenmaterialprozesstechnikGyrotron
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The increasing demand for powerful, reliable, and efficient gyrotron oscillators for Electron Cyclotron Resonance Heating (ECRH) in fusion plasma experiments requires a close look at the various factors in gyrotrons that determine gyrotron performance. In this frame, the influence of emitter surface roughness, emission inhomogeneity, and secondary electron generation on gyrotron operation is presented, with focus on Low Frequency Oscillations (LFOs) and Electron Beam Halo (EBH) generation.
Strahlsysteme --- Emitter --- Low Frequency Oscillations --- Magnetron Injection Gun --- Gyrotron --- Electron Beam Halo --- Electron Beam HaloGyrotron
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In this work, a novel measurement system for the analysis of the gyrotron RF output spectrum was developed. It enables unprecedented time dependent measurements within a large bandwidth, dynamic range and unambiguous RF indication in the entire D-Band (110-170 GHz). Special attention was given to the investigation of parasitic RF oscillations, and the analysis of the interplay of thermal cavity expansion and ionization-based space charge neutralization at the start of long RF pulses.
spectrum analysis --- Mikrowellenmesstechnik --- millimeter waves --- Gyrotron --- Spektralanalyse --- Millimeterwellen --- microwave measurement techniques
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The DEMOnstration fusion power plant (DEMO) will be the first fusion reactor, which is intended to generate net electrical power. For successful operation of DEMO, high-power gyrotrons with operating frequencies up to 240 GHz are required for plasma heating and stabilization. In this work, a systematic feasibility study and tolerance analysis are performed for the conventional-type hollow-cavity DEMO gyrotrons. The various approaches are also suggested to identify its operational limits.
Hollow-cavity --- Hohlleitergyrotron --- Kernfusion --- Frequenz durchstimmbarkeit --- Gyrotron --- DEMO --- Nuclear Fusion --- Frequency Tunability
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Dynamic after-cavity interaction (ACI) in megawatt-class gyrotrons is investigated that could lead to lower output mode purity and increased level of internal stray radiation. The self-consistent KIT-IHM multi-mode-code SELFT has been modified to extend the simulation domain into the radius up-taper section of the gyrotron cavity where the probability of ACI exists. Studies on four different gyrotron configurations confirm that undesired interactions in the up-taper region can result in additional parasitic oscillations with relative power in the 1%-range.
After-Cavity Interaction --- Fusion Plasmas --- Electron-Cyclotron-Heating --- High-Power Gyrotron
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The last decade has contributed to the rapid progress in developing high-power microwave sources. This Special Issue aims to bring together information about the most striking theoretical and experimental results, new trends in development, remarkable modern applications, new demands in parameter enhancement, and future goals. Although only a tiny part of the achievements of recent years is included in this Issue, we hope that the presented articles will be useful for experts and students focusing on modern vacuum electronics.
Technology: general issues --- Energy industries & utilities --- velocity ratio --- velocity spread --- low-voltage --- gyrotrons --- MIG --- particle simulation --- space charge effects --- pillbox window --- wide-band --- W-band --- low loss --- mode converter --- 220 GHz --- taper --- terahertz --- traveling-wave tube --- folded waveguide (FWG) --- slow wave system --- high harmonic traveling wave tube --- gyrotron --- quasi-optical cavity --- confocal waveguide --- frequency tuning --- high power --- sub-millimeter wave --- PFN-Marx --- compact --- modular --- trigger source --- gas switch --- mica capacitor --- millimeter waves --- wireless power transmitting --- quasi-optical antenna --- gaussian beam --- Gyrotron --- sub-terahertz --- high-power microwave source --- HPM source --- virtual cathode oscillator --- vircator --- ring reflector --- high-power electromagnetic waves (HPEM) --- semiconductor --- failure threshold time --- microwave hardness --- electromagnetic pulse (EMP) shielding --- broadband --- gyro-TWT --- high-resolution imaging radar --- TE02 mode --- dielectric properties --- low-reflection barrier windows --- broadband window --- microwaves --- terahertz radiation --- velocity ratio --- velocity spread --- low-voltage --- gyrotrons --- MIG --- particle simulation --- space charge effects --- pillbox window --- wide-band --- W-band --- low loss --- mode converter --- 220 GHz --- taper --- terahertz --- traveling-wave tube --- folded waveguide (FWG) --- slow wave system --- high harmonic traveling wave tube --- gyrotron --- quasi-optical cavity --- confocal waveguide --- frequency tuning --- high power --- sub-millimeter wave --- PFN-Marx --- compact --- modular --- trigger source --- gas switch --- mica capacitor --- millimeter waves --- wireless power transmitting --- quasi-optical antenna --- gaussian beam --- Gyrotron --- sub-terahertz --- high-power microwave source --- HPM source --- virtual cathode oscillator --- vircator --- ring reflector --- high-power electromagnetic waves (HPEM) --- semiconductor --- failure threshold time --- microwave hardness --- electromagnetic pulse (EMP) shielding --- broadband --- gyro-TWT --- high-resolution imaging radar --- TE02 mode --- dielectric properties --- low-reflection barrier windows --- broadband window --- microwaves --- terahertz radiation
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The last decade has contributed to the rapid progress in developing high-power microwave sources. This Special Issue aims to bring together information about the most striking theoretical and experimental results, new trends in development, remarkable modern applications, new demands in parameter enhancement, and future goals. Although only a tiny part of the achievements of recent years is included in this Issue, we hope that the presented articles will be useful for experts and students focusing on modern vacuum electronics.
Technology: general issues --- Energy industries & utilities --- velocity ratio --- velocity spread --- low-voltage --- gyrotrons --- MIG --- particle simulation --- space charge effects --- pillbox window --- wide-band --- W-band --- low loss --- mode converter --- 220 GHz --- taper --- terahertz --- traveling-wave tube --- folded waveguide (FWG) --- slow wave system --- high harmonic traveling wave tube --- gyrotron --- quasi-optical cavity --- confocal waveguide --- frequency tuning --- high power --- sub-millimeter wave --- PFN-Marx --- compact --- modular --- trigger source --- gas switch --- mica capacitor --- millimeter waves --- wireless power transmitting --- quasi-optical antenna --- gaussian beam --- Gyrotron --- sub-terahertz --- high-power microwave source --- HPM source --- virtual cathode oscillator --- vircator --- ring reflector --- high-power electromagnetic waves (HPEM) --- semiconductor --- failure threshold time --- microwave hardness --- electromagnetic pulse (EMP) shielding --- broadband --- gyro-TWT --- high-resolution imaging radar --- TE02 mode --- dielectric properties --- low-reflection barrier windows --- broadband window --- microwaves --- terahertz radiation --- n/a
Choose an application
The last decade has contributed to the rapid progress in developing high-power microwave sources. This Special Issue aims to bring together information about the most striking theoretical and experimental results, new trends in development, remarkable modern applications, new demands in parameter enhancement, and future goals. Although only a tiny part of the achievements of recent years is included in this Issue, we hope that the presented articles will be useful for experts and students focusing on modern vacuum electronics.
velocity ratio --- velocity spread --- low-voltage --- gyrotrons --- MIG --- particle simulation --- space charge effects --- pillbox window --- wide-band --- W-band --- low loss --- mode converter --- 220 GHz --- taper --- terahertz --- traveling-wave tube --- folded waveguide (FWG) --- slow wave system --- high harmonic traveling wave tube --- gyrotron --- quasi-optical cavity --- confocal waveguide --- frequency tuning --- high power --- sub-millimeter wave --- PFN-Marx --- compact --- modular --- trigger source --- gas switch --- mica capacitor --- millimeter waves --- wireless power transmitting --- quasi-optical antenna --- gaussian beam --- Gyrotron --- sub-terahertz --- high-power microwave source --- HPM source --- virtual cathode oscillator --- vircator --- ring reflector --- high-power electromagnetic waves (HPEM) --- semiconductor --- failure threshold time --- microwave hardness --- electromagnetic pulse (EMP) shielding --- broadband --- gyro-TWT --- high-resolution imaging radar --- TE02 mode --- dielectric properties --- low-reflection barrier windows --- broadband window --- microwaves --- terahertz radiation --- n/a
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