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在室温下采用化学沉淀法制备了铽掺杂的羟基磷灰石(Tb-HAP),通过X射线衍射分析(XRD)、傅里叶变换红外光谱(FT-IR)和荧光光谱(PL)等对其结构和荧光性能进行了表征分析。XRD和FT-IR测试表明,Tb3+的掺杂对羟基磷灰石的结构没有显著影响。荧光光谱分析表明:在545 nm波长监测下,测得的最佳激发波长为378 nm。样品的发光强度随Tb3+在样品中的掺杂摩尔分数先增大后减小,在8%时发光最强。此外,Tb-HAP样品的荧光寿命随着Tb3+掺杂摩尔分数的增加呈现减小的趋势。 相似文献
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A novel slotted helix slow-wave structure (SWS) is proposed to develop a high power, wide-bandwidth, and high reliability millimeter-wave traveling-wave tube (TWT). This novel structure, which has higher heat capacity than a conven- tional helix SWS, evolves from conventional helix SWS with three parallel rows of rectangular slots made in the outside of the helix tape. In this paper, the electromagnetic characteristics and the beam-wave interaction of this novel structure operating in the Ka-band are investigated. From our calculations, when the designed beam voltage and beam current are set to be 18.45 kV and 0.2 A, respectively, this novel circuit can produce over 700-W average output power in a frequency range from 27.5 GHz to 32.5 GHz, and the corresponding conversion efficiency values vary from 19% to 21.3%, and the maximum output power is 787 W at 30 GHz. 相似文献
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An open-styled dielectric-lined azimuthally periodic circular waveguide for a millimeter wave traveling-wave tube 下载免费PDF全文
An open-styled dielectric-lined azimuthally periodic circular waveguide (ODLAP-CW) for a millimeter-wave traveling-wave tube (TWT) is proposed, which is a modified form of a dielectric-lined azimuthally periodic circular waveguide (DLAP-CW). The slow-wave characteristics of the open-styled DLAP-CW are studied by using the spatial harmonics method, which includes normalized phase velocity and interaction impedance. The complicated dispersion equations are numerically solved with MATLAB and the results are in good agreement with the simulation results obtained from HFSS. The influence of structural parameters on the RF properties is investigated based on our theory. The numerical results show that the optimal thickness of the metal rod can increase the interaction impedance, with the dielectric constant held fixed. Finally, the slow-wave characteristics and transmission properties of an open-styled structure are compared with those of the DLAP-CW. The results validate that the mode competition is eliminated in the improved structure with only a slight influence on the dispersion characteristics, which may significantly improve the stability of an open-styled DLAP-CW-based TWT, and the interaction efficiency is also improved. 相似文献
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研究了三种新型的曲折波导慢波系统,分别是曲折双脊波导、脊加载曲折波导和矩形槽加载曲折波导。给出了其高频特性的理论和仿真结果。然后介绍了基于常规曲折波导和脊加载曲折波导慢波系统的Ka 波段行波管的实验结果。 相似文献
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在对周期性结构进行谐波分析的基础上,导出了非截面二维光子晶体排列矩形波导的本征值方程. 基于此方程,可以对该类光子晶体波导的所有可能模式进行分析. 分析认为,非截面二维光子晶体排列矩形波导内能存在的模式包括E(y),TEy,H(y)和TMy模式;改变波导高度,可以实现E(y)模式和H(y)模式与其他模式通带的完全分离. 然而改变任一结构参数,都不能使E(y)和H(y)的各个模式通带,以及E(y)1模式和H(y)1模式的通带完全隔离. 波导单模工作的带宽由E(y)1和E(y)2模式的低端截止频率决定.
关键词:
波导
光子晶体
本征值方程
模式 相似文献
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优化设计了一种220 GHz的折叠波导慢波结构的尺寸,对其冷测特性如色散、耦合阻抗和衰减进行了分析。理论分析和软件仿真结果表明设计的折叠波导慢波结构在中心频率处具有较平缓的色散关系,较高的耦合阻抗和较低的电路衰减。互作用模拟表明,在电子注电压为20 kV,电流为10 mA时,27 mm(50个周期)的折叠波导慢波结构在220 GHz具有14.5 dB的增益,3 dB带宽为16.3 GHz(211.9~228.2 GHz)。 相似文献