共查询到20条相似文献,搜索用时 296 毫秒
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Shirong Bu Zhengxiang LuoKai Yang Bowan Tao 《Physica C: Superconductivity and its Applications》2010,470(22):2002-2005
A simple bridged resonator method is presented for microwave nonlinearity measurement of epitaxial superconductor thin film. By this method, microwave current is concentrated in local bridged part on the resonator, and local inductive and resistive nonlinearity in this part are measured. At the same time, undesired nonlinearity are eliminated from the tested results by the special current distribution of the resonator, which enhances the accuracy of the measured nonlinearity. 相似文献
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ZENG Hao RAO Jun 《核工业西南物理研究院年报(英文版)》2005,(1):63-64
To carry out lower hybrid wave heating and current drive plasma experiment on tokamak, we need mega-watt order of microwave power generated by the parallel-running klystrons. Those klystrons must be driven by the microwave exciter. Now our microwave exciter is used for many years and its performance is decreased very much. It can not satisfy any more the hybrid wave heating and current drive plasma experiment. So we set out to design a new microwave exciter that is consist of the microwave solid components, amplitudestabilization control, modularization design with multitude-outputs, microwave phase control in order to satisfy the demand of the different work in the hybrid wave heating and current drive plasma experiment. 相似文献
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R. J. Temkin K. E. Kreischer W. J. Mulligan S. MacCabe H. R. Fetterman 《International Journal of Infrared and Millimeter Waves》1982,3(4):427-437
The design and operation of a 100 kW, 140 GHz pulsed gyrotron are reported. To our knowledge, this is the highest frequency at which high gyrotron output power (>-100 kW) has been achieved. Results are presented for gyrotron operation in the range of magnetic field from 4 to 7 T, voltage from 23 to 80 kV and current up to 7.5 A. Near a value of magnetic field of 5.4 T, and output power of 100 kW was obtained at 140.4 GHz in single mode operation in the TE031 resonator mode. 相似文献
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描述了一种延长EPR波谱仪中速调管使用寿命的方法.根据这种方法,只要正确地调谐微波桥的工作状态和适当地调整功率电平器的功率校正电平.即使对于已经严重老化的速调管仍然可以继续使用一段时间,维持仪器的正常运行. 相似文献
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Non-resonant microwave absorption (NRMA) studies of superconducting MgB2 and a sample containing ∼10% by weight of MgO in MgB2 are reported. The NRMA results indicate near absence of intergranular weak links in the pure MgB2 sample. A linear temperature dependence of the lower critical field H
c1 is observed indicating a non-s wave superconductivity. However, the phase reversal of the NRMA signal which could suggest d wave symmetry is also not observed. In the MgB2 + MgO sample, much larger low field dependent absorption is observed indicating the presence of intergranular weak links.
The hysteretic behavior of NRMA is compared and contrasted in the two samples. In the pure MgB2 sample, a large hysteresis is observed between the forward and the reverse scans of the magnetic field indicating strong
pinning of flux lines. This hysteresis saturates a few degrees below T
c while in the MgB2 + MgO sample, a much slower increase of hysteresis with decreasing temperature is observed, a signature of weaker pinning. 相似文献
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A.A. Bykov A.K. Bakarov A.K. Kalagin A.V. Goran A.I. Toropov S.A. Vitkalov 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):97
The effect of microwave radiation in the frequency range from 1.2 to 10 GHz on the magnetoresistance of a high-mobility two-dimensional electron gas has been studied in a GaAs quantum well with AlAs/GaAs superlattice barriers. It has been found that the microwave field induces magnetoresistance oscillations periodic in the reciprocal magnetic field (1/B). It has been shown that the period of these oscillations in the covered frequency range depends on the microwave radiation power. 相似文献
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We present new investigations of the millimeter wave spectra of the two lowest-energy conformers of glycine (NH2CH2COOH). Measurements of these spectra have been carried out between 75 and 260 GHz using the millimeter-wave spectrometer in Kharkov. The new data set involves rotational transitions with J up to 44 and Ka up to 15 for conformer I and transitions with J up to 43 and Ka up to 14 for conformer II. This represents a more than twofold expansion both in the frequency range and J quantum-number range in comparison with previous investigations. The improved sets of spectroscopic parameters obtained for both conformers provide accurate transition frequencies for the key lines necessary for radio astronomy searches for interstellar glycine. 相似文献
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A photonic approach to realizing instantaneous measurement of microwave frequency based on optical monitoring using a fiber Bragg grating (FBG) is proposed and demonstrated. In the approach, a frequency-unknown microwave signal is modulated on an optical carrier in a Mach-Zehnder modulator biased at the minimum transmission point. After detecting the transmission and reflection optical powers at the output of the FBG, the microwave frequency can be determined according to the value of transmission-to-reflection power ratio, due to the fixed relationship between the microwave frequency and the power ratio. A proof-of-concept experiment has been performed, which demonstrates that a measurement resolution of ±0.08 GHz over a 10 GHz measurement bandwidth is achieved. The measurement performance in terms of resolution is better than previously reported results. 相似文献
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David Bouis Pascal Febvre 《International Journal of Infrared and Millimeter Waves》2008,29(12):1156-1162
Sets of bow-tie antennas, used in a single emitter-receiver near-field configuration and in array configuration, have been
studied to be used as wireless means to transmit 8–12 GHz microwave signals from the cold stage of a cryogenic system to a
room-temperature processing unit. Indeed, the absence of heat conduction allows increasing the performance of cryogenic systems
and open the way to multichannel microwave systems that are necessary for imagers. Transmission loss has been found to be
lower than 3 dB over a 1.5 GHz bandwidth while crosstalk in the array configuration is kept below −20 dB when antennas are
located at around 90 mm transversally from each other. 相似文献