Gyro-TWT is one of the most promising candidates for the application of the transmitter microwave source of the next-generation imaging radar; meanwhile, it plays an important role in national security. Gyro-TWT with helical waveguide is capable of generating broad-bandwidth radiation, as well as high stable ability. In this paper, we derive the dispersion equation of helical waveguide and the non-linear theory of calculating the beam-wave interaction. Numerical stimulation results accord with the experimental results. We design a W-band gyro-TWT operating at a 80 keV, 5 A electron beam, which can produce an output power of 142 kW, with 3 dB bandwidth 4.5%, cantral frequency 95 GHz and saturation gain 52 dB. Finally, we calculate the effect of variation of voltage and current on the output performance of gyro-TWT with helical waveguide.

螺旋波纹波导回旋行波管与采用光滑圆波导的回旋管相比,有较大的带宽.介绍了该类回旋行波管的非线性注波互作用理论.计算结果表明该理论计算结果与实际实验报道的结果基本符合,相应的电子效率达到29％,饱和增益达到37 dB,工作磁场0.21 T,电压185 kV,电流19A.

Mode competition induces non-stationary oscillations during the operation of a gyrotron backward-wave oscillator (gyro-BWO), which severely reduces its tunable bandwidth and output power. Self-consistent nonlinear theory is used to study the modes-competition mechanism of a W-band fundamental TE01 mode gyro-BWO. Tapered non-resonant interaction circuit structure and loading lossy ceramic are employed to suppress the competing modes, as a way of preventing non-stationary oscillation in the circuit. Systematically optimized interaction circuit is capable of suppressing all the competing modes and can stably operate in the fundamental axial mode of the TE01 mode. Calculation indicates that a peak power of 105 kW and a -3 dB tunable bandwidth of 5.4% are attainable. This is meaningful and provides a theoretical foundation for developing broadband millimeter gyro-BWOs in the applications of counter-measure system, non-destructive detection, plasma diagnosis, material processing, and so on.

螺旋波纹波导回旋行波管与采用圆波导的回旋行波管相比,有较大的带宽.介绍了它的线性注波互作用理论,并用该理论计算了不同的磁场与波导表面微扰幅度对Ka波段螺旋波纹波导回旋行渡管线性增益的影响.计算结果与已报道的实验结果基本符合,说明该理论可以初步确定螺旋波纹波导回旋行波管的各项参数.

High efficiency is one of the essential requirements for modern space Traveling Wave Tube(TWT) development,and a single percentage point increase of overall efficiency is very significant to translate into potential revenue increases.The enhancement of overall efficiency was realized by optimizing the helix pitch profile of a TWT to maximize the collector efficiency.The maximum collector efficiency of a TWT normally conflicts with the basic beam-wave interaction efficiency.Such a conflict has been mitigated via setting the electronic efficiency higher than 25% as a constraint of the algorithm to ensure a high output power.The 3-D large signal Beam-Wave Interaction Simulator(BWIS)of MTSS,which was employed to calculate the output power and the energy distribution of the spent beam,was integrated with the Genetic algorithm.The detailed design of a Ku-band helix traveling wave was described and maximum collector efficiency of 89% with electronic efficiency of 26.9% was achieved from the simulation results.

Mechanism of mode coupling for Gyro-TWT with helical interaction waveguide is interpreted in this article,which derived from equivalent boundary conditions and exciting equation. TE1,1 will excited TE_2,1 in helical interaction waveguide. Furthermore, TE_2,1 is primarily coupled with-1 harmonic of TE1,1.

Nanopores with diameters between 30 nm and 180 nm have been fabricated by inducing latent track with fast heavy ions and etching process in 25 μm thick, singlecrystal muscovite mica. For short etching time, the nanopores are columns with circular cross section. For long etching time the cross section of nanopores becomes rhombic. Thus the shape of nanopores depends on the etching time. Cu nanowires have been fabricated with controlled dimensions by electrodeposition into the nanopores. The ultravioletvisible light absorption spectra of Cu nanowires embedded in mica templates show that the circular Cu nanowires with diameter smaller than 60 nm exhibit one intense resonance peak and one smaller peak. With increasing diameter of the nanowires， the intense peak is redshifted while the smaller peak strengthens gradually. The diameter and shape can tune the optical properties of Cu nanowires. The morphology and crystallinity of the Cu nanowires were studied by means of scanning electron microscopy and Xray diffraction.

CdS nanowires and nanotubes were prepared by electrodeposition method in etched ion-track polycarbonate(PC) templates.By using the templates with different pore sizes,cylindrical CdS nanowires and nanotubes were obtained with the diameter between 20 and 100 nm,and hexagonal polycrystalline in nature.The morphology and crystallinity of the CdS nanowires and nanotubes were studied by means of scanning electron microscopy(SEM),X-ray diffraction(XRD),and transmission electron microscopy(TEM).The one-dimensional semiconductor nanostructure with controlled dimension can be easily synthesized in etched ion-track templates.

Polypyrrole(PPy) nanowires were prepared by electrochemical polymerization in etched ion-track polycarbonate(PC) membranes.The diameters of nanowires are between 100 and 320 nm,and the maximum length is up to 30 μm.The nanowires were characterized using field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM) and ultraviolet-visible(UV-Vis) spectrophotometer.The results show that as-prepared PPy nanowire is regular cylinder with smooth surface and homogeneous diameter.It's also interesting to find that there is a thin layer of ordered polymer chains at nanowire's outer surface and that the extent of this chain order decreases toward the center of the nanostructure.The UV-Vis absorption spectra of PPy nanowires embedded in PC membranes show that,with increasing diameters of nanowires,the absorption peak related to PPy nanowires shifts to longer wavelength.

The 3-D structures in silicon are increasingly coming to use in many fields.For example,the high resolution X-ray digital imaging detector can be made by coupling CCD and the scintillating screen which is made by the array trenches filled with CsI(Tl).In the present work,we explored the technology of etching micro-array on the n-type silicon with high resistance.By studying the relative parameters of anisotropic etching of KOH and electro-chemical etching of HF,the optimized concentration of HF was determined and the micro-pore array trenches with 200 μm in depth were realized.The results establish an experimental base for further fabrication of the scintillating screen.

Nanopores with rhombic shape were obtained by heavy ion irradiation and track etching single-crystal muscovite mica sheet of thickness 25 μm.The rhombic cross sectional shape has a major diameter of around 50 nm and a minor diameter of around 30 nm.The Au nanowires were fabricated by electrodeposition into the mica nanopores.The UV-Vis absorption spectra of Au nanowires show that the Au nanowires exhibite two surface plasma resonance(SPR) peaks due to the rhombic shape.The morphology and crystallinity of the Au nanowires were studied by means of scanning electron microscopy(SEM) and X-ray diffraction(XRD) analyses.

Polycarbonate (PC) membranes were irradiated with swift heavy ions and latent tracks were created along the ions' trajectories. Nanopores, diameters between 100 and 500 nm, were obtained after illuminating the membranes with UV light and etching in NaOH solution. Silver nanowires were produced in the etched ion-track membranes by electrochemical deposition. The morphology and crystallinity of the silver nanowires were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). Under certain conditions (deposition voltage 25 mV, current density 1-2 mA.cm(-2), temperature 50 degrees C, electrolyte 0.1 mol.L-1 AgNO3), single-crystalline silver nanowires with preferred orientation along the [111] direction can be synthesized.

Under the vacuum and room temperature environment,polyethyleneterephthalate(PET),polycarbonate(PC,Makrofol KG) and polyimide(PI) foil stacks were irradiated with various swift heavy ions(1.158GeV Fe56,1.755GeV Xe136 and 2.636GeV U238) . The damage processes in the irradiated polymer latent tracks were studied by X-ray diffraction(XRD),Fourier Transform Infrared(FTIR) spectroscopy and ultraviolet/visible(UV/Vis) spectroscopy in a very wide electronic stopping power range(from 1.9 to 17.1 keV·nm-1) and fluence range from 1×1010 to 3×1012 ions·cm-2. The degradation of main functional group,alkyne formation,amorphization and red shift of the absorption edge were observed. By quantitatively analyzing the main damages and applying the saturated track model,the mean damage radii of tracks of amorphization and alkyne formation process were obtained for Fe,Xe and U ion irradiation,respectively. The results were explained by the theoretical model.