共查询到20条相似文献,搜索用时 31 毫秒
1.
Chong-Qing Jiao Ji-Run Luo 《Journal of Infrared, Millimeter and Terahertz Waves》2007,28(12):1095-1101
This study proposes a Ka-band harmonic-doubling gyrotron traveling-wave amplifier (gyro- TWT), using distributed wall losses in the input stage and mode-selective interaction circuit in the output stage, to improve the stability of the amplification. Based on a large signal simulation code, a saturated peak power of 163 kW with an efficiency of 15.5%, a gain of 31.1 dB, and a 3 dB bandwidth of 0.9 GHz is predicted for the gyro-TWT driven by 70 kV, 15 A electron beam with a velocity ratio of 1.2 and velocity spread 5% at 33.2 GHz. 相似文献
2.
Johan Rothman Kevin Foubert Gilles Lasfargues Christophe Largeron 《Journal of Electronic Materials》2014,43(8):2947-2954
The impulse response time has been measured as a function of reverse bias, gain, and temperature in backside-illuminated short-wave infrared HgCdTe avalanche photodiodes (APDs) with variable junction geometry. The APD geometry was altered using HgCdTe substrates of variable thickness and by variation of device fabrication parameters. This approach allowed study of the drift–diffusion dynamics of the electrons before entering the junction and the electron and hole dynamics during the junction transition in APDs with different carrier collection distances and junction widths. The response time was typically limited by a double exponential decay, which is attributed to contributions from the impedance mismatch between the interconnection circuit and the 50-Ω radiofrequency probe, and a delayed diffusion response from carriers generated far from the junction. These contributions limited the maximum bandwidth of the diodes to about 600 MHz, independently of gain and temperature. The hot carrier velocities are estimated by fitting the measured response with numerical calculations, taking into account contributions from a direct drift–multiplication response and a delayed diffusion response. This analysis shows that the hot carrier dynamics is close to independent of temperature and that the electron drift velocity saturates at the gain onset to a value of 1 × 107 cm/s, decreasing upon a further increase of the electric field E to a value of about 3 × 106 cm/s at E = 100 kV/cm. The hole velocity shows a slow variation from 3 × 106 cm/s at low electric fields to 1.5 × 106 cm/s at high electric fields. 相似文献
3.
In this paper, the behavior of the electrical conductivity of epoxy/silicon carbide (SiC) composites as a function of weight fraction and particle size of SiC at room temperature has been investigated. Composite samples were prepared by a mixture composed of the same amount of hardener and resin (5 mg) with different amounts (ranging from 5 mg to 7 mg) of silicon carbide powder with different grain sizes (400 and 800 grit). The conduction current was measured under different applied voltages from 1 to 10 kV (corresponding to applied electrical fields from 0.04 kV/mm to 0.4 kV/mm), and the composites microstructure was characterized by scanning electron microscopy. It was shown that the electrical conductivity of epoxy/SiC composites was found to increase when the weight fraction of SiC was increased and also to increase non-linearly as a function of the electrical field. 相似文献
4.
The possibility of improving bunching and rising efficiency by using a cavity that operates at the second harmonics of working frequency has been studied. This possibility is realized in relativistic gyroklystrons with rather high-density electron beams. The three-cavity gyroklystrons with full length l=5.2λ, accelerating voltage V0=425 kV, and beam current I0=160 A have been studied. In this letter, a new solution to the problem of electron-phase-bunching improvement in gyroklystrons is suggested. It allows one to design a new construction of gyroklystrons 10% more effective than traditional designs 相似文献
5.
《Electron Devices, IEEE Transactions on》1969,16(12):1002-1009
A theoretical investigation of the influence of a spatially varying drift velocity on the perturbations in magnetically focused electron beams is presented. The wave propagation on such beams, focused by infinite magnetic fields, is studied under the small-wave assumption. The dispersion relation for slow waves is derived and solved for different transversal boundary conditions. Two sets of infinitely many propagating modes are found in a beam with small velocity shear. In a beam with sufficiently large velocity shear only two eigenfunctions exist. Since it is not possible to match the two eigenfunctions on arbitrary longitudinal boundary conditions, additional solutions (which cannot be written in form of a plane wave) must exist. The excitation of perturbations by ideal grids is solved by introducing the Laplace transform analysis. Additional solutions are ascertained which lead to a spatial decay of the perturbations according to a power law z-α. This damping, arising from the spatially varying drift velocity, is similar to the Landau damping in electron beams with velocity distribution. Such damping effects are of great practical importance in conjunction with noise reduction in traveling-wave tubes. 相似文献
6.
Sung Gug Kim Ashwini Sawant Ingeun Lee Dongsung Kim MunSeok Choe Jong-Hyo Won Jungho Kim Joonho So Won Jang EunMi Choi 《Journal of Infrared, Millimeter and Terahertz Waves》2016,37(3):209-229
A high-power W-band gyrotron has been designed and performance tested in Korea, with an output power in the range of tens of kilowatts. The gyrotron consists of a diode-type electron gun operating at 40 kV, a TE6,2 mode interaction cavity, and a mode converter for producing a highly Gaussian output mode beam. Presented here are the detailed component design procedure and the experimental results of the gyrotron’s performance evaluation. A maximum power of 62 kW was achieved with an efficiency of 22 %, and a highly Gaussian output beam was observed. The gyrotron’s output beam is analyzed, and its transmission through an oversized waveguide is discussed. This gyrotron is the first gyrotron developed in Korea with high power greater than 10 kW and high frequency greater than 90 GHz. 相似文献
7.
The results are presented of a series of experimental and analytical investigations into the minimum requirements of a DC ignition source for non-contact arc ignition. Conditions for ignition are found—the starting discharge voltage should be less than the output voltage of the main source and it should exist for a time governed by the transient behaviour of the circuit and the discharge supplied by the two power sources during ignition. A design example shows that for a typical welding supply of 80 V output, the ignition source must have an output voltage of at least 4 kV and an output current of at least 0.5 A for at least 56 µs to initiate a 3 mm TIG welding arc. 相似文献
8.
Nitin Kumar Udaybir Singh Anirban Bera A. K. Sinha 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(11):1342-1356
In this paper, we present the RF behavior of conventional cylindrical interaction cavity for 240 GHz, 1 MW gyrotron for futuristic plasma fusion reactors. Very high-order TE mode is searched for this gyrotron to minimize the Ohmic wall loading at the interaction cavity. The mode selection process is carried out rigorously to analyze the mode competition and design feasibility. The cold cavity analysis and beam-wave interaction computation are carried out to finalize the cavity design. The detail parametric analyses for interaction cavity are performed in terms of mode stability, interaction efficiency and frequency. In addition, the design of triode type magnetron injection gun is also discussed. The electron beam parameters such as velocity ratio and velocity spread are optimized as per the requirement at interaction cavity. The design studies presented here confirm the realization of CW, 1 MW power at 240 GHz frequency at TE46,17 mode. 相似文献
9.
S. A. Kishko A. N. Kuleshov M. Yu. Glyavin I. V. Zotova I. V. Zheleznov N. S. Ginzburg V. N. Manuilov V. Yu. Zaslavskii 《Journal of Communications Technology and Electronics》2014,59(7):777-781
The opportunity of generating ribbon-shaped polyhelical electron beams intended to excite oscillations in the new type of gyrotrons is investigated via particle-in-cell simulation. Its distinctive features are the planar geometry of an interaction space and transverse energy extraction (with respect to the direction of translational motion of a helical electron beam). The electrode configuration has been found in the gyrotron with an operating frequency 75 GHz, where the formed electron beam has a velocity spread of ~10%, the rotational energy fraction is 50%, and the beam profile is weakly distorted. When the voltage is 12 kV and the beam current is 1 A, the electron beam under study is demonstrated to excite the single-mode generation with an efficiency of up to 15% in the gyrotron’s operating space produced by the planar waveguide. 相似文献
10.
介绍在L波段强流相对论速调管研究中,强流相对论短脉冲空心电子束的产生、传输、束流调制及其诊断等方面的初步实验研究情况。在直线感应加速器上,利用66mm、壁厚3mm的石墨空心阴极,加上约5kGs的准直流引导磁场,引出了约500kV、4.5kA、脉宽100ns、54.5mm、厚度4.5mm的空心电子束。注入500kW的微波调制,束流经过输入腔后,得到了约6%的最大基波电流调制深度,经过中间腔后,得到了约23%的基波电流调制深度。 相似文献
11.
设计了工作在X波段的同轴多注相对论速调管放大器,建立了带输入、输出波导结构的三维整管模型,采用三维电磁粒子模拟软件对其高频特性进行了优化设计,对电子束经过输入腔后的束流调制、注入微波吸收情况、中间腔对束流的调制以及输出腔的微波提取情况进行了模拟研究.在输入微波功率为70kW,电子束束压为600kV,束流为5kA,轴向引导磁感应强度为0.6T的条件下,输出微波功率达到了1.3GW,效率为43%,增益为42dB,在较低的输入微波功率和较小的轴向引导磁感应强度的情况下,模拟实现了X波段RKAGW级的微波功率输出. 相似文献
12.
Toshitaka Idehara Kosuke Kosuga La Agusu Ryosuke Ikeda Isamu Ogawa Teruo Saito Yoh Matsuki Keisuke Ueda Toshimichi Fujiwara 《Journal of Infrared, Millimeter and Terahertz Waves》2010,31(7):775-790
A high frequency gyrotron with a 15 T superconducting magnet named Gyrotron FU CW VI has achieved continuous frequency tuning through the relatively wide range of 1.5 GHz near 400 GHz. The operation is at the fundamental cyclotron resonance of the TE06 cavity mode with many higher order axial modes. The output power measured at the end of the circular waveguide system ranges from 10 to 50 watts at the low acceleration voltage of 12 kV for beam electrons. The beam current is also low. It is around 250 mA. This gyrotron is designed as a demountable radiation source for the 600 MHz DNP-NMR spectroscopy. The design and operation results of the gyrotron FU CW VI are presented. 相似文献
13.
Suzana Domingues Daniele Perenzoni Matteo Perenzoni David Stoppa 《Journal of Infrared, Millimeter and Terahertz Waves》2017,38(6):679-688
In this paper, a switched-capacitor readout circuit topology integrated with a THz antenna and field-effect transistor detector is analyzed, designed, and fabricated in a 0.13-μm standard CMOS technology. The main objective is to perform amplification and filtering of the signal, as well as subtraction of background in case of modulated source, in order to avoid the need for an external lock-in amplifier, in a compact implementation. A maximum responsivity of 139.7 kV/W, and a corresponding minimum NEP of 2.2 nW/√Hz, was obtained with a two-stage readout circuit at 1 kHz modulation frequency. The presented switched-capacitor circuit is suitable for implementation in pixel arrays due to its compact size and power consumption (0.014 mm2 and 36 μW). 相似文献
14.
S. Sabchevski T. Idehara I. Ogawa M. Glyavin S. Mitsudo K. Ohashi H. Kobayashi 《Journal of Infrared, Millimeter and Terahertz Waves》2000,21(8):1191-1209
Results from computer aided design of a novel electron gun generating axis-encircling beams are presented and discussed. Numerical experiments were performed by the new version of the software package GUN-MIG named GUN-MIG/CUSP. It is based on a self-consistent relativistic model and is developed as a problem oriented tool for analysis of electron-optical systems with magnetron injection guns (MIG) and electron guns with field reversal (cusp guns), forming axis-encircling beams. As a result of the simulations an electron-optical design of a novel electron gun with permanent magnet system was accomplished. The gun is expected to form high quality beams with small velocity spread and beam ripple. Parameters of the generated beams are appropriate for a prospective weakly relativistic high harmonic large orbit gyrotron (LOG). The development of such device is in progress now at the Research Center for Development of Far-Infrared Region (FIR Center) at Fukui University. 相似文献
15.
K. D. PENDERGAST B. G. DANLY W. L. MENNINGER R. J. TEMKIN 《International Journal of Electronics》2013,100(5-6):983-1004
Results of a long-pulse, cyclotron autoresonance maser (CARM) oscillator experiment are reported. A Stanford accelerator (SLAC 5045) klystron gun produced a 1 pis electron beam at 250-300 kV and 10-25 A at a repetition rate of up to 4 Hz. A beam α≡β⊥/β1, variable from 0 to 1, was produced on this electron beam with a wiggler magnetic field near guide field resonance. The experiments were carried out with two different Bragg reflection resonators designed for the TE11 mode. Using the first resonator, many harmonic gyrotron modes were observed in the 28-40GHz frequency range in the TE21 and TE01 modes and, for the first time, a second harmonic upshifted (CARM) TE11 mode at 74-5 GHz. Using the second resonator, fundamental CARM operation was observed for many parameter settings, and for frequencies ranging from 29 to 32 GHz. Output powers ranged from ~01 kW to l00kW, resulting in efficiencies of 01% to 2%. Identification of CARM and gyrotron modes is made by comparison of measured frequencies with dispersion theory and measurement of the farfield radiation pattern. Comparison with theory indicates that the device efficiency is reduced by finite spread in the axial electron beam momentum. 相似文献
16.
介绍了 FEL-THz装置中电子枪控制系统的设计与实现过程。利用 Microsoft公司发布的 Visual C++6.0进行了控制系统软件的开发和设计。实验结果显示,该软件操作简捷,具有良好的人机操作界面,程序实时响应速度快,运行稳定,为电子枪高压老炼以及系统测评提供支持。 相似文献
17.
Electron beams with a continuous current density of 800 A/cm2were extracted from a synthesized-plasma hollow cathode. The beams were accelerated up to potentials of 1.2 kV, through the potential of maximum ionization probability at about 16 volts. There was no accompanying oscillation or gas breakdown. This high voltage operation was made possible by collimating the cesium vapor entering the hollow cathode. The collimation, which was accomplished by use of a narrow slit at the "top" of the cathode, caused the vapor to flow along the cathode wall surface and away from the exit aperture. This minimized escape of neutrals into the high voltage region. The cathode was tested for 200 hours without any signs of degradation. The cathode lifetime is predicted to be several thousand hours at the highest cathode temperature (2425°K) employed in these studies. The extracted 0.030-in diameter beam of 0.250-in length had an electron temperature of less than twice cathode temperature. Longer beams, such as would be used in actual microwave tubes, would require magnetic confinement. 相似文献
18.
L. K. Varga 《Journal of Electronic Materials》2014,43(1):117-120
The Finemet-type nanocrystalline alloy represents an advanced soft-magnetic metal–metal-type nanocomposite with an eddy-current-determined high- frequency limit. A survey of different heat treatments under tensile stress is presented to tailor the hysteresis loop by induced transversal anisotropy. The flattened loop having reduced effective permeability enhances the eddy- current limit in the MHz region; For example, continuous stress annealing in a tubular furnace of 1 m length at 650°C, pulling the ribbon with a velocity of 4 m/min under a tensile stress of 200 MPa, results in a wound core having a permeability of 120 and a frequency limit of 10 MHz. Careful annealing preserves the static coercivity below 10 A/m. The power loss at 0.1 T and 100 kHz is only 82 mW/cm3, which is an order of magnitude lower then the values obtained for Sendust? cores in similar conditions. 相似文献
19.
V. N. Manuilov T. Idehara T. Saito La Agusu T. Hayashi I. Ogawa 《Journal of Infrared, Millimeter and Terahertz Waves》2008,29(12):1103-1112
High power short pulse gyrotron with operating frequency 395 GHz operating on the second cyclotron harmonic is now under developing at FIR FU. The gyrotron is planned to use in future experiments for plasma diagnostics. For this purpose the output power about 100 kW and pulse duration 100 ns at least are needed. Preliminary estimations of parameters of some versions of the electron guns with accelerating potential U0?=?70-100 kV were performed. Possibilities of non-adiabatic as well as adiabatic guns were considered. It was shown that non-adiabatic system is not reliable for such rather low value of U0, the adiabatic magnetron injection gun (MIG) is more preferable for the gyrotron design. Analytical estimations of the suitable MIG dimensions and operating regime to form good quality electron beam were fulfilled. Numerical optimization of the gun shape and position was performed. It was shown that in spite of the extremely big ratio of the operating current (I0?=?18 A) to the Langmuir current of the gun, close to 0.4-0.5, the suggested MIG can form the helical electron beam (HEB) which is suitable for gyrotron operation properties. 相似文献
20.
《Electron Devices, IEEE Transactions on》1967,14(8):438-443
A method is devised for determining the eigenvalue spectra of the characteristic noise matrix of electron beams with continuous velocity distributions. It is found that for an electron beam with a half-Maxwellian velocity distribution, all positive eigenvalues are equal to kTΔf while all negative eigenvalues approach zero. This finding is in agreement with the phenomenon of noise reduction in an electron beam drifting at a low average velocity (an average velocity comparable to the velocity spread). 相似文献