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Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Digital microwave relay communication system is a multichannel communication system in which digital signals are transmitted by microwave relay. In order to improve the signal-to-noise ratio and reduce the bit error rate in this kind of communication, a C-band sharp roll down broadband metamaterial absorber is designed in study. The quasi-periodic ring resonant structure is used to realize the polarization insensitive broadband absorption effect. The absorption efficiency is more than 90% in the range of 7~8 GHz, and the rolling down coefficient of the absorption line can reach more than 0.8. Based on the common structure, a dielectric layer is added to the proposed metamaterial absorber, which protects the ring structure of the surface of the metamaterial absorber and increases the impedance matching ability of the absorber. The proposed design has the characteristics of simple structure, thin thickness, common material and sharpe roll down absorption, and has important application potential in the fields of detection, stealth, sensing, communication and so on. [ABSTRACT FROM AUTHOR]

In order to meet the power source requirements of C-band linear accelerators for industrial applications, a C-band high power klystron operating at a frequency of 5 712 MHz was developed. For this klystron, the development objective of the output power is no less than 3.5 MW and the efficiency is no less than 35%. During the entire design process, the output power was optimized to over 4 MW and the power efficiency over 40% to compensate for the disadvantage effects caused by manufacturing and testing errors in the development processes. Firstly, the electron optics system with a Pierce gun and a combination of five forward and one reverse focusing coils was designed. The Pierce gun with a perveance of 2 μP was adopted and the beam voltage and current were chosen as 120 kV and 83.3 A. By iteratively calculating the structure of the electron gun with EGUN code and optimizing the magnetic field between the electron gun and the beam-wave interaction section, the final electron beam pass rate reaches 100% and the fluctuation of the beam envelop is only 4.8%. Secondly, the efficiency optimization and PIC simulation of the beam-wave interaction section were carried out using the one dimensional AJDISK code, 1.5 dimensional KlyC code and three dimensional CST code. The scheme of six resonant cavities was ultimately determined and the basic cavity parameters were optimized based on the principles of stagger tuning. The simulation results of different codes all indicate that the efficiency can reach above 46.5%, and the output power can all reach above 4.650 MW. And the influence of frequency errors and output external quality factor on efficiency was also analyzed to guide the manufacturing process. After that, the mechanical structure of cavities was designed and all cavities were manufactured with oxygen free copper. The cold test and tuning of all cavities were carried out and the frequency error is mostly within the range of ±5 MHz, which basically does not affect the output power. Finally, the electron gun, the beam-wave interaction section and the collector were welded together. And the high power test was conducted immediately after the first high power C-band klystron protype was completed. When the electron gun operates at the voltage of 115 kV and current of 79.6 A, the klystron peak output power reaches 3.52 MW, the gain reaches 45.5 dB and the efficiency reaches about 38.5%. The high power test results show that this C-band high power klystron achieves the expected development goals.

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

C-band high-power microwave devices have important application prospects in communication, radar and other fields, and the demand for compact and lightweight devices is becoming more and more urgent in the industrial sector. A C-band high-efficiency coaxial transit-time oscillator (CTTO) with three-cavity buncher and dual-cavity extractor is proposed and investigated in theory and 2.5-dimensional particle-in-cell simulations, which is good for high power microwave generation devices at low frequency towards miniaturization and compactness. In order to avoid the transverse electromagnetic mode (TEM) leaking to the diode region, the reflector is designed and adopted in front of the buncher, which also can pre-modulate the beams and lead to the higher conversion efficiency. In this simulation, the typical performance of the CTTO reveals that microwaves with a power of 1.83 GW are generated at a frequency of 6.37 GHz when the beam voltage and current are 458 kV and 9.6 kA respectively, under a guiding magnetic field of 1.05 T. The corresponding power conversion efficiency is as high as 41.6%. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Test & Measurement Technology is the property of Publishing Center of North University of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to develop a compact electron linear accelerator, a C-band on-axis coupled standing wave accelerating tube operating at the frequency of 5 712 MHz was developed in this paper. The designed beam energy is 6 MeV, and the designed pulse beam current intensity is greater than 80 mA. Firstly, in order to achieve the compact goal, the beam dynamics design was carried out based on the RF phase focusing theory. By designing the phase velocity distribution and electric field distribution in the whole tube reasonably, the longitudinal bunching and transverse focusing of the electron beam were realized simultaneously without external focusing magnetic field. Secondly, the structure of this C-band accelerating tube was optimized after establishing the equivalent circuit model to obtain the required electric field distribution. This accelerating tube adopted π/2 mode onaxis coupled standing wave structure and was composed of three bunching cavities and nine uniform accelerating cavities with a total length of about 284 mm. Through the analysis of the equivalent model, the relationship between the cavity parameters and the coupling coefficient between adjacent cavities were revealed. After adjusting the basic parameters of each cavity, the structure of this tube was determined and the required electric field distribution was obtained. Then the input coupler was designed to match the coupling requirement and the RF field got from the simulation of the whole tube was used in the beam dynamics validation calculation. At last, cavities were brazed together after tuned to the designed frequency and the cold test and highpower test of this tube were carried out. The reflection parameters of this tube were tested in the vacuum condition. The test results show that the operating frequency is 5 7136 MHz, the reflection coefficient at the operating frequency is -16.5 dB, and the corresponding input coupling is 1.35, which meets the designed requirements. The electric field distribution was tested according to the bead-pull measurement method and it’s consistent with the designed field distribution. In the high-power test, the tube was driven by a C-band magnetron which delivered a 2.5 MW peak power, 4 μs width pulse with a repetition rate of 250 Hz. An X-ray target was placed at the beam exit and the maximum dose rate at 1 m behind the target is 845 cGy/min, which indicates that the beam pulse current is 84.5 mA. Based on the half-value-layer measurement methods, the test result shows the electron beam energy can reach 6 MeV. These test results verify the validity of the development process of C-band 6 MeV on-axis coupled standing wave accelerating tube.

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a trapezoidal periodically poled magnesium doped lithium niobate (PPMgLN) waveguide was designed, and its acceptable bandwidth of the pump source during frequency doubling (SHG) process can be widened by introducing a temperature gradient along the propagation direction. The effective refractive index of the waveguide was calculated and the dimension of the waveguide was designed by the finite difference beam propagation method. The results show that, by changing the temperature at different positions of the trapezoidal waveguide to form a temperature gradient, the wavelength receiving bandwidth of the pump light source can be widened. The maximum receiving bandwidth of the PPMgLN waveguide pump light source designed in this paper is C-band, which range is from 1 530 nm to 1 565 nm. The waveguide can double the frequency of C-band, and the output band bandwidth is 765 nm to 782. 5 nm, and the temperature tuning range is from 30 °C to 150 °C. [ABSTRACT FROM AUTHOR]

In order to extend the transmission distance of the traditional C-band high-speed optical module, this paper studies a kind of quasi-coherent reception technology based on the existing 25 Gbit/s optical module, and discusses the application scheme of the quasi-coherent reception technology. It is found that the quasi-coherent receiver can effectively reduce the influence of dispersion on the transmission distance of high-speed optical module without using additional electrical or optical dispersion compensation technology. The experimental results show that the quasi-coherent receiver has strong processing ability for optical signals degraded by dispersion, and the use of the quasi-coherent receiver can significantly improve the transmission sensitivity of the optical module. The experimental results show that the quasi-coherent reception technology can extend the transmission distance of the C-band 25 Gbit/s optical module with traditional intensity modulation technology from 10 km to more than 25 km.

Copyright of Study on Optical Communications / Guangtongxin Yanjiu is the property of Study on Optical Communications Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A new configuration of the low noise figure C+L-band erbium-doped fiber amplifier was proposed and demonstrated.In the proposed configuration,a preamplifier was used to reduce the noise figure,and an improved double-pass configuration with a fiber bragg grating was employed to enhance the L-band gain and while to reduce the noise figure.The experiment results demonstrate that the noise figure in the new broad-band amplifier was improved by −2 dB,and the gain was enhanced up to above 25 dB over the region from 1 525～1 605 nm.

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)