In this study,uniform diamond films with a diameter of 100 mm were deposited in a 15 kW/2.45 GHz ellipsoidal microwave plasma chemical vapour deposition system.A phenomenological model previously developed by our grou...In this study,uniform diamond films with a diameter of 100 mm were deposited in a 15 kW/2.45 GHz ellipsoidal microwave plasma chemical vapour deposition system.A phenomenological model previously developed by our group was used to simulate the distribution of the electric strength and electron density of plasma.Results indicate that the electric field in the cavity includes multiple modes,i.e.TM_(02) and TM_(03).When the gas pressure exceeds 10 kPa,the electron density of plasma increases and plasma volume decreases.A T-shaped substrate was developed to achieve uniform temperature,and the substrate was suspended in air fromφ70 to 100 mm,thus eliminating vertical heat dissipation.An edge electric field was added to the system after the introduction of the T-shaped substrate.Moreover,the plasma volume in this case was greater than that in the central electric field but smaller than that in the periphery electric field of the TM_(02) mode.This indicates that the electric field above and below the edge benefits the plasma volume rather than the periphery electric field of the TM_(02) mode.The quality,uniformity and surface morphology of the deposited diamond films were primarily investigated to maintain substrate temperature uniformity.When employing the improved substrate,the thickness unevenness of theφ100 mm diamond film decreased from 22%to 7%.展开更多
The superconducting tokamak HT-7U [1] has been designed by the Institute of Plasma Physics since 1998 and will be set up before 2003. The 1.2 MW /2.45 GHz HT-7U LHCD (Lower hybrid current drive) system which being the...The superconducting tokamak HT-7U [1] has been designed by the Institute of Plasma Physics since 1998 and will be set up before 2003. The 1.2 MW /2.45 GHz HT-7U LHCD (Lower hybrid current drive) system which being the most efficient non-induction device can heat the plasma and drive the plasma current has been efficiently in operation 'owl and a particular design of the 2.8 MW/-35 kV high-voltage DC power supply has been already completed and will apply to the klystron of LHCD on HT-7 and the future HT-7U, and the project of the power supply has been examined and approved professionally by an authorized group of high-level specialist in the institute of Plasma Physics. The detailed design of the power supply and the simulation results are referred in the paper.展开更多
A novel surface wave plasma （SWP） source excited with cylindrical Teflon waveguide has been developed in our previous work. The plasma characteristics have been simply studied. In this work, our experimental device ...A novel surface wave plasma （SWP） source excited with cylindrical Teflon waveguide has been developed in our previous work. The plasma characteristics have been simply studied. In this work, our experimental device has been significantly improved by replacing the Teflon waveguide with a quartz rod, and then better microwave coupling and higher gas purity can be obtained during plasma discharge. The plasma spatial distributions, both in radial and axial directions, have been measured and the effect of gas pressure has been investigated. Plasma density profiles indicate that this plasma source can produce uniform plasma in an axial direction at low pressure, which shows its potential in plasma processing on a curved surface such as an inner tube wall. A simplified circular waveguide model has been used to explain the principle of plasma excitation. The distinguishing features and potential application of this kind of plasma source with a hardware improvement have been shown.展开更多
The dielectric property of organic reagent is key to the study of Microwave-assisatant organic synthesization.The data of complex permittivity of these organic reagents can not be obtained easy.The complex permittvity...The dielectric property of organic reagent is key to the study of Microwave-assisatant organic synthesization.The data of complex permittivity of these organic reagents can not be obtained easy.The complex permittvity of these organic regents were measured in 2.45 GHz by cavity perturbation method.The result shows that the real and imaginary parts of the permittivity of alcohol are larger than others.The real part of the complex permittivity of ketone is larger and the imaginary part is smaller.The real and imaginary parts of the permittivity of acid are smaller.The real and imaginary parts of the permittivity of alkyl and benzene are the smallest.The real part and the imaginary parts of the permittivity of all decrease while the increasing of the number of carbon’s chain.The analysis and the measurement offer high helps in the microwave assistant organic synthesization.展开更多
基金sponsored by National Key Research and Development Program of China(No.2019YFE03100200)National Natural Science Foundation of China(No.5210020483)+1 种基金Postdoc Research Foundation of Shunde Graduate School of University of Science and Technology Beijing(No.2020BH015)Fundamental Research Funds for the Central Universities(No.FRF-MP-20-48)。
文摘In this study,uniform diamond films with a diameter of 100 mm were deposited in a 15 kW/2.45 GHz ellipsoidal microwave plasma chemical vapour deposition system.A phenomenological model previously developed by our group was used to simulate the distribution of the electric strength and electron density of plasma.Results indicate that the electric field in the cavity includes multiple modes,i.e.TM_(02) and TM_(03).When the gas pressure exceeds 10 kPa,the electron density of plasma increases and plasma volume decreases.A T-shaped substrate was developed to achieve uniform temperature,and the substrate was suspended in air fromφ70 to 100 mm,thus eliminating vertical heat dissipation.An edge electric field was added to the system after the introduction of the T-shaped substrate.Moreover,the plasma volume in this case was greater than that in the central electric field but smaller than that in the periphery electric field of the TM_(02) mode.This indicates that the electric field above and below the edge benefits the plasma volume rather than the periphery electric field of the TM_(02) mode.The quality,uniformity and surface morphology of the deposited diamond films were primarily investigated to maintain substrate temperature uniformity.When employing the improved substrate,the thickness unevenness of theφ100 mm diamond film decreased from 22%to 7%.
文摘The superconducting tokamak HT-7U [1] has been designed by the Institute of Plasma Physics since 1998 and will be set up before 2003. The 1.2 MW /2.45 GHz HT-7U LHCD (Lower hybrid current drive) system which being the most efficient non-induction device can heat the plasma and drive the plasma current has been efficiently in operation 'owl and a particular design of the 2.8 MW/-35 kV high-voltage DC power supply has been already completed and will apply to the klystron of LHCD on HT-7 and the future HT-7U, and the project of the power supply has been examined and approved professionally by an authorized group of high-level specialist in the institute of Plasma Physics. The detailed design of the power supply and the simulation results are referred in the paper.
基金supported in part by National Natural Science of Foundation of China(Nos.11005021,51177017 and 11175049)the Grants-in-Aid for Scientific Research of Japan Society for the Promotion of Science(No.21110010)+1 种基金the Fudan University Excellent Doctoral Research Program(985 project)the Ph.D Programs Foundation of Ministry of Education of China(No.20120071110031)
文摘A novel surface wave plasma （SWP） source excited with cylindrical Teflon waveguide has been developed in our previous work. The plasma characteristics have been simply studied. In this work, our experimental device has been significantly improved by replacing the Teflon waveguide with a quartz rod, and then better microwave coupling and higher gas purity can be obtained during plasma discharge. The plasma spatial distributions, both in radial and axial directions, have been measured and the effect of gas pressure has been investigated. Plasma density profiles indicate that this plasma source can produce uniform plasma in an axial direction at low pressure, which shows its potential in plasma processing on a curved surface such as an inner tube wall. A simplified circular waveguide model has been used to explain the principle of plasma excitation. The distinguishing features and potential application of this kind of plasma source with a hardware improvement have been shown.
文摘The dielectric property of organic reagent is key to the study of Microwave-assisatant organic synthesization.The data of complex permittivity of these organic reagents can not be obtained easy.The complex permittvity of these organic regents were measured in 2.45 GHz by cavity perturbation method.The result shows that the real and imaginary parts of the permittivity of alcohol are larger than others.The real part of the complex permittivity of ketone is larger and the imaginary part is smaller.The real and imaginary parts of the permittivity of acid are smaller.The real and imaginary parts of the permittivity of alkyl and benzene are the smallest.The real part and the imaginary parts of the permittivity of all decrease while the increasing of the number of carbon’s chain.The analysis and the measurement offer high helps in the microwave assistant organic synthesization.
