Perturbation method of boundary geometry(PMOBG) used in Lapiacian problems is dealt with and the three--term perturbation expression of distributed capacitance of a coaxial line with perturbed walls is obtained. As an...Perturbation method of boundary geometry(PMOBG) used in Lapiacian problems is dealt with and the three--term perturbation expression of distributed capacitance of a coaxial line with perturbed walls is obtained. As an example,four-order expression of distributed capacitance of a elliptic coaxial line with small eccentricity is given.展开更多
1.5MW Ion Cyclotron Wave Heating system was developed, the transmitter and the antenna both have their ground loops, which will severely perturb the system’s normal operation. To avoid perturbation, a DC break was de...1.5MW Ion Cyclotron Wave Heating system was developed, the transmitter and the antenna both have their ground loops, which will severely perturb the system’s normal operation. To avoid perturbation, a DC break was designed. The S parameter and the VSWR (voltage standing wave ratio) of incident port were calculated; the thermal effect caused by conductor loss and dielectric loss was analyzed.展开更多
A TTF-type coaxial higher order modes (HOM) coupler has been used in a TESLA 9 cell cavity. It is impossible to measure the stop band characteristics of the HOM coupler with the cavity. A measurement device for the ...A TTF-type coaxial higher order modes (HOM) coupler has been used in a TESLA 9 cell cavity. It is impossible to measure the stop band characteristics of the HOM coupler with the cavity. A measurement device for the coaxial transmission line type for the HOM coupler has been designed at Peking University. Experimentally it was shown that the average voltage standing wave ratio of the coaxial transmission line is smaller than 1.08. The experimental results of the stop band characteristics of the TTF-type HOM coupler have been fitted for the simulation. This paper describes the design of the measurement device and discusses the experimental and simulation results of stop band characteristics of the HOM coupler.展开更多
A new waveguide to coaxial line transition adopted to microwave band is proposed in this paper.The configuration and design of the transition is studied. It has the merits of simplicity in structure, ease ofconstructi...A new waveguide to coaxial line transition adopted to microwave band is proposed in this paper.The configuration and design of the transition is studied. It has the merits of simplicity in structure, ease ofconstruction and repeatable performance, especially that the coaxial line is in the same direction with thewaveguide. At X band, the pass bandwidth of the transition is about 6%, and the insertion loss less than 1dB.展开更多
An updated main coupler has been designed for the superconducting accelerator of Free Electron Laser (FEL) project under construction in Peking University. A capacitive structure is chosen for the main coupler. Nume...An updated main coupler has been designed for the superconducting accelerator of Free Electron Laser (FEL) project under construction in Peking University. A capacitive structure is chosen for the main coupler. Numerical investigation using CST Microwave Studio demonstrates the cold window part. The other nonstandard structures such as holding rods and antenna are also optimized. The coupler uses a 95% purity Al2O3 ceramic cold window. The VSWR (Vottage Standing Wave Ratio) is 1.02 at 1.3 GHz and the frequency bandwidth is 45 MHz with VSWR〈I.1. The electric field intensity is 8.5× 10-2 kV/mm around the window with 20 kW Continuous Wave (CW) transmitted power. The Qext is designed variable from 5× 10^8 to 1×10^7.展开更多
This paper describes the fabrication of a waveguide and the analysis of its polarization characteristics by applying light-emitting diode(LED) pumping lights to its surface.By using double tubed coaxial line(DTCL) mic...This paper describes the fabrication of a waveguide and the analysis of its polarization characteristics by applying light-emitting diode(LED) pumping lights to its surface.By using double tubed coaxial line(DTCL) microwave plasma chemical vapor deposition(MPCVD) equipment,an a-Si:H/SiN multilayer waveguide was fabricated whose thickness could be controlled at nanometer order.The main structural material of the waveguide sample consisted of a combination of layers of amorphous silicon hydrogen and silicon nitrate.Once the sample was ready,another major objective of the experiment was to analyze the polarization characteristics of the fabricated waveguide.The idea of the experiment was to analyze how the waveguide reacts when three types of LED(blue,yellow,and red) are radiated onto its surface.The results showed that the fabrication of the a-Si:H/SiN sample is successful.Most effective transmission results,which accord with the polarization characteristics analysis,were obtained.展开更多
基金the Open Foundation of State Key Laboratory of Advanced Technology for Materials Synthersis Processing
文摘Perturbation method of boundary geometry(PMOBG) used in Lapiacian problems is dealt with and the three--term perturbation expression of distributed capacitance of a coaxial line with perturbed walls is obtained. As an example,four-order expression of distributed capacitance of a elliptic coaxial line with small eccentricity is given.
基金The project supported by the National Science Foundation of China (No. 10274089) National High Technology Program of China
文摘1.5MW Ion Cyclotron Wave Heating system was developed, the transmitter and the antenna both have their ground loops, which will severely perturb the system’s normal operation. To avoid perturbation, a DC break was designed. The S parameter and the VSWR (voltage standing wave ratio) of incident port were calculated; the thermal effect caused by conductor loss and dielectric loss was analyzed.
基金National Natural Science Foundation of China (10276001)
文摘A TTF-type coaxial higher order modes (HOM) coupler has been used in a TESLA 9 cell cavity. It is impossible to measure the stop band characteristics of the HOM coupler with the cavity. A measurement device for the coaxial transmission line type for the HOM coupler has been designed at Peking University. Experimentally it was shown that the average voltage standing wave ratio of the coaxial transmission line is smaller than 1.08. The experimental results of the stop band characteristics of the TTF-type HOM coupler have been fitted for the simulation. This paper describes the design of the measurement device and discusses the experimental and simulation results of stop band characteristics of the HOM coupler.
文摘A new waveguide to coaxial line transition adopted to microwave band is proposed in this paper.The configuration and design of the transition is studied. It has the merits of simplicity in structure, ease ofconstruction and repeatable performance, especially that the coaxial line is in the same direction with thewaveguide. At X band, the pass bandwidth of the transition is about 6%, and the insertion loss less than 1dB.
基金Supported by National Basic Research Program(2002CB713600)NSFC(10775010)
文摘An updated main coupler has been designed for the superconducting accelerator of Free Electron Laser (FEL) project under construction in Peking University. A capacitive structure is chosen for the main coupler. Numerical investigation using CST Microwave Studio demonstrates the cold window part. The other nonstandard structures such as holding rods and antenna are also optimized. The coupler uses a 95% purity Al2O3 ceramic cold window. The VSWR (Vottage Standing Wave Ratio) is 1.02 at 1.3 GHz and the frequency bandwidth is 45 MHz with VSWR〈I.1. The electric field intensity is 8.5× 10-2 kV/mm around the window with 20 kW Continuous Wave (CW) transmitted power. The Qext is designed variable from 5× 10^8 to 1×10^7.
基金supported by the Waseda University Undergraduate Fund,Japan, and Malaysia Majlis Amanah Rakyat (MARA) through the MARA Scholarship Foundation
文摘This paper describes the fabrication of a waveguide and the analysis of its polarization characteristics by applying light-emitting diode(LED) pumping lights to its surface.By using double tubed coaxial line(DTCL) microwave plasma chemical vapor deposition(MPCVD) equipment,an a-Si:H/SiN multilayer waveguide was fabricated whose thickness could be controlled at nanometer order.The main structural material of the waveguide sample consisted of a combination of layers of amorphous silicon hydrogen and silicon nitrate.Once the sample was ready,another major objective of the experiment was to analyze the polarization characteristics of the fabricated waveguide.The idea of the experiment was to analyze how the waveguide reacts when three types of LED(blue,yellow,and red) are radiated onto its surface.The results showed that the fabrication of the a-Si:H/SiN sample is successful.Most effective transmission results,which accord with the polarization characteristics analysis,were obtained.