共查询到20条相似文献,搜索用时 93 毫秒
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Walter M.T. Gilgenbach R.M. Luginsland J.W. Hochman J.M. Rintamaki J.I. Jaynes R.L. Lau Y.Y. Spencer T.A. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1996,24(3):636-647
Computer modeling has been utilized to guide gyrotron backward-wave oscillator (gyro-BWO) experiments at the University of Michigan over a wide range of tapered interaction regions and tapered magnetic fields. E-GUN code is used to examine beam and diode characteristics, while MAGIC is used to analyze the dynamics of the problem, such as particle kinematics and microwave power production. Several innovative techniques are used to create matching boundary conditions for a backward propagating wave. MAGIC simulations predict optimum performance of the gyro-BWO operating in a TE01 mode within a combination of uniform interaction region and a tapered axial magnetic field which increases 7.5% in the direction of beam propagation. Experiments have been performed to investigate the effects of tapering magnetic fields and tapered interaction region radii on the high-power microwave emission from the gyro-BWO over the frequency range from 4.0 to 6.0 GHz. These experiments were performed on the Michigan Electron Long-Pulse Accelerator (MELBA) with parameters: V=-0.7 to -0.9 MV, Idiode=1-10 kA, Itube=1-4 kA, Te-beam =0.4-1.0 μs. Tapered interaction regions of 37%, 23%, 9.4%, and 6.4% were built and tested to determine their effect on microwave power, pulselength, and inferred energy compared to the uniform interaction region. Magnetic tapering trim coils with a range of -10.6%<ΔB/B0<+15.0% were constructed which allow the orientation of the field taper to be changed without breaking the vacuum. The peak microwave power from individual shots was from 30 to 55 MW. Experiments on magnetic field tapering indicate that positive tapered fields improve microwave power and energy output 相似文献
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An experimental study was carried out to test the concept of using a gyrotron with a tapered circuit in a uniform magnetic field as a high-power tunable source of millimeter-wave radiation. It was demonstrated that the device can be used as either an oscillator or an amplifier with the operating frequency tunable by varying the magnetic field. In the oscillator mode, the tube produced a peak output power of 500-750 W with the frequency continuously tunable from 30 to 39 GHz. As an amplifier mode, the tube demonstrated an electronic gain of ~23 dB at a magnetically tunable center frequency with an instantaneous bandwidth of ~5 percent. The stability characteristics of the amplifier were also investigated. 相似文献
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V. S. Chursin E. N. Odarenko A. A. Shmat'ko 《International Journal of Infrared and Millimeter Waves》1996,17(7):1165-1180
The two-dimensional model of millimeter wave resonant O-type oscillator (as orotron, ledatron, resonant BWO, etc.) with a relativistic electron beam is analyzed. The selfconsistent nonlinear simultaneous equations have been obtained for the arbitrary space distribution of the magnetic guide field. The start generation characteristics are analyzed under small-signal conditions with an analytical solution taken for the case of inclined focusing magnetic field. It is found that the efficiency of electron-wave interaction appreciably depends on the focusing field strength and the relativistic mass factor. The results of numerical optimization of the guide field structure are presented to show possibility of improvement of the start characteristics of the oscillator. 相似文献
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利用二维半的PIC等离子体物理程序设计了一种新的结构简单、体积小、重量轻、频率稳定的高功率、高效率的微波器件。此器件采用了锥形慢波结构波导谐振腔,不用外加引导磁场。微波频率可以设计为f=1.6 ~12GHz,功率Pout可达GW。 相似文献
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采用2.5维粒子模拟软件对改进型低阻类膜片加载同轴渡越时间振荡器进行了研究。研究结果表明:提取腔工作于类模场时,具有较高的束波互作用效率;引入渐变型输出波导,提高了提取腔内微波向外耦合输出的能力;通过加载感性支撑杆,一方面对金属膜片起支撑固定作用,另一方面可以及时将膜片上的感应电荷导流至接地外筒、从而降低间隙附近的空间电荷效应,以增加可提取的束动能。经优化设计,该结构在二极管电压为530 kV,二极管电流为12.9 kA、外加导引磁场为0.5 T的条件下,输出微波功率2.74 GW,微波频率7.76 GHz,束波功率转换效率达40%。 相似文献
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Freund H.P. Ganguly A.K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(3):245-255
Results obtained with the three-dimensional nonlinear analysis and simulation code, ARACHNE, and a recent 33.4-GHz, collective, free-electron laser (FEL) amplifier experiment are compared. The experiment has demonstrated power levels of 61 MW (≈27% efficiency) without recourse to tapered magnetic fields, using a 750-keV/300-A electron beam with a nominal axial energy spread of 1.5% propagating through a cylindrical drift tube in the presence of a helical wiggler and an axial guide magnetic field. Significant differences in the character of the emission were found, depending on the direction of the guide magnetic field. When the wiggler and guide fields were parallel, observed power levels reached approximately 4 MW for both the strong and weak guide field regimes, but vanished in the neighborhood of the magnetic resonance. However, the maximum power was observed in the reversed field case when the wiggler and guide fields were antiparallel. In this case, no resonant enhancement in the transverse velocity is expected to occur; however, a significant reduction in the output power occurred in the neighborhood of the antiresonance. The ARACHNE simulation is in substantial agreement with the experiment 相似文献
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Results of theoretical and experimental investigations into a relativistic backward wave oscillator with a modulating resonant
reflector are generalized. The modulating resonant reflector is used to reflect a counter propagating wave and guide it toward
an electron collector. It is shown that premodulation of the electron beam near the reflector may have a significant effect
on the starting conditions of oscillation; selective properties of the oscillator; and its efficiency, which may reach 40%
when a high-current beam is transported by a strong magnetic field. In the reduced magnetic fields that were employed in the
pulsed-periodic regime and were 1.5–2.0 times lower than those at which cyclotron resonance with the counter propagating wave
is observed, the oscillator efficiency (30–35% at a wavelength of 8 mm) is limited by position and velocity spreads of particles.
Mechanical pulsewise frequency tuning within about 10% at a repetition rate of 1–50 Hz and a multigigawatt microwave power,
as well as a rise in the power and energy of microwave pulses via an increase in the cross-sectional dimensions of the slow-wave
structure, are demonstrated to be feasible. 相似文献
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M. A. Alexanyan K. S. Aramyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2007,42(2):49-54
We study the equations of motion of a spherical oscillator model suggested by Bellucci and Nersessian, in the presence of a constant magnetic field. This model is shown to be exactly solvable classically in contrast to the Higgs oscillator which is not exactly solvable in magnetic fields. 相似文献
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结合负载限制型磁绝缘线振荡器(MILO)和渐变型MILO的特点提出并设计了P波段混合型MILO的结构,主要以负载限制型MILO结构作为雏形,将其内部仅含有的1根提取叶片用3根长度渐变的慢波叶片组成的渐变段替换。该结构可更好地实现束波相互作用,并使提取间隙电场与MILO输出同轴结构处的电场达到更好的匹配,增加微波输出功率。器件纵向总长度为47 cm,外筒直径为44 cm。优化后的2.5维全电磁粒子模拟结果表明:在二极管工作电压550 keV、电流约57 kA的情况下,输出微波的中心频率为640 MHz,平均功率为4.27 GW,束波转换效率为13.6%,器件4 ns时起振,6 ns达到饱和,且微波输出功率十分稳定,最终输出微波模式为TEM模。 相似文献
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Marder B.M. Clark M.C. Bacon L.D. Hoffman J.M. Lemke R.W. Coleman P.D. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(3):312-331
A compact device, called a split-cavity oscillator, whose self-excited oscillating electromagnetic field converts a large-area steady electron beam into one that is highly density modulated, is described. It does this in a short beam travel length, easing both space-charge and pinching limitations. Thus, high currents are possible without requiring a magnetic guide field. Methods for converting the modulated output beam into high-power microwaves are discussed, as are ways to phase-lock several oscillators together. Analytic theory, numerical simulations, and experiments describing the device are presented 相似文献
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Jing-Feng Miao 《International Journal of Infrared and Millimeter Waves》1992,13(4):433-441
A new millimenter-wave Gunn oscillator is described. The present structure makes use of NRD guide and metal resonant cap. The field expressions and the design considerations of NRD guide are discussed. Some experimental results of 8mm and 6mm band oscillators show that the new Gunn oscillator has a future as an integrated millimeter-wave source.This work was supported by National Natural Science Foundation of China 相似文献
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在耦合波理论的基础上,结合波导渐变曲线给出了普适高阶渐变波导设计方法,研究了95 GHz回旋管内置 TE03模式改进Dolph-Chebychev渐变波导。采用编制的数值计算程序进行优化,得到了可靠的最优几何参量,设计出了紧凑的95 GHz渐变波导。经全电磁场仿真验证,该内置渐变输出结构对杂模的抑制达30 dB,满足设计要求。回旋管的热测实验中测出的模式样图表明,所设计的内置渐变波导有效地实现了回旋管内径变化。该方法可以高效地指导高阶过模圆波导渐变结构的设计。 相似文献
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模拟研究了一种在均匀慢波结构后增加渐变慢波结构段的太赫兹过模表面波振荡器,获得了输出功率和模式纯度的显著提高。首先根据S参数方法,研究分析了这种复合高频结构中TM_(01)模的谐振特性。然后采用2.5维PIC(Particle-in-cell)软件UNIPIC,模拟研究了振荡器输出性能随渐变慢波结构周期数的变化关系。结果表明:随着周期数的增加,输出太赫兹波中的TM_(02)和TM_(03)等高次模成分降低,TM_(01)模的功率比例增大至80%以上;选择合适长度的渐变慢波结构,能使得器件输出功率增大50%。 相似文献