Radio frequency （RF） underwater discharge operation was performed for different liquid conductivities driven by different frequencies ranging from 13.56 MHz to 60 MHz, and its application to organic degradation was ...Radio frequency （RF） underwater discharge operation was performed for different liquid conductivities driven by different frequencies ranging from 13.56 MHz to 60 MHz, and its application to organic degradation was investigated. The RF underwater discharge was observed to be generated within the bubble at electrode surface formed by RF and plasma heating. It was shown that the sizes of the bubbles and plasmas increased as the driving frequency and the input power went up. The breakdown voltage decreased rapidly with the increase of the water conductivity and driving frequency. Comparative experiments of the UV-VIS absorbance spectra of Congo Red solution before and after discharge suggested effective degradation of the organic dye due to the active species generated during the discharge, such as .OH, .O, .H, etc. revealed by optical emission spectroscopy. The results show that higher exciting frequency and lower conduc- tivity of the solution are more effective for organic degradation. With the combination of Fourier Transform Infrared Spectroscopy （FT-IR） and Liquid Chromatography-Mass Spectrometry （LC- MS） data, one possible degradation process was proposed and the main conceivable components and structures of the products were also presented.展开更多
In our previous work, a plasma approach for single attosecond pulse （AP） generation was proposed. A few-cycle relativistic circularly polarized laser pulse will induce a single drastic oscillation of plasma boundary...In our previous work, a plasma approach for single attosecond pulse （AP） generation was proposed. A few-cycle relativistic circularly polarized laser pulse will induce a single drastic oscillation of plasma boundary, from which high-order harmonics and furthermore an ultra-intense single AP can be generated naturally after it is reflected. Analytical model and simulations both demonstrate that the process is mostly efficient as the pulse duration is close to the plasma responding time. The effects of plasma density ramp are analyzed here, suggesting that the proposal is still quite efficient with appropriate density gradient in the ramp. At last, a combined approach is employed to obtain single AP with 30 fs incident laser. The relatively large-duration pulse is firstly shortened by a density dropping thin foil, and then reflected from an overdense plasma target. One-dimensional simulation shows that a 600 as single light pulse is generated with peak intensity of 3×10^20 W/cm^2.展开更多
The plasma density and electron temperature of a multi-source plasma system composed of several collisional inductively coupled plasma （ICP） cells were measured by a doubleprobe. The discharges of the ICP cells were...The plasma density and electron temperature of a multi-source plasma system composed of several collisional inductively coupled plasma （ICP） cells were measured by a doubleprobe. The discharges of the ICP cells were shown to be independent of each other. Furthermore, the total plasma density at simultaneous multi-cell discharge was observed to be approximately equal to the summation of the plasma density when the cells discharge separately. Based on the linear summation phenomenon, it was shown that a larger area plasma with a uniform density and temperature profile could be constructed with multi-collisional ICP cells.展开更多
Two dimensional particle-in-cell simulations are taken to study the interaction of a circularly polarized laser pulse with a nano-scale micro-structured target. The protons which are doped in the rear side of the targ...Two dimensional particle-in-cell simulations are taken to study the interaction of a circularly polarized laser pulse with a nano-scale micro-structured target. The protons which are doped in the rear side of the target experience the electrostatic fields caused by both the radiation pressure driven shock and the target normal sheath at the rear side of the target. A quasimonoenergetic proton bunch with central energy of about 11MeV and energy spread of ＆#8710; ε/ε about 0.18 is achieved by using a 3.45×1019 W/cm2, 66fs laser pulse. A comparison with the case of linearly polarized laser pulse and the same target condition is considered.展开更多
A scheme of generating energetic ions by the interaction of an ultrahigh-intensity laser pulse and a thin solid foil is studied. The combination of the effects of radiation pressure and Coulomb explosion makes the ion...A scheme of generating energetic ions by the interaction of an ultrahigh-intensity laser pulse and a thin solid foil is studied. The combination of the effects of radiation pressure and Coulomb explosion makes the ion acceleration more effective. The maximum ion velocity variation with time is predicted theoretically while the temporal evolution of the electrostatic field due to the Coulomb explosion is taken into consideration. Two-dimensional particle-in-cell simulations are done to verify the theory.展开更多
基金supported by Natural Science Foundation of Jiangsu Education Committee of China (No.09KJA140005)
文摘Radio frequency （RF） underwater discharge operation was performed for different liquid conductivities driven by different frequencies ranging from 13.56 MHz to 60 MHz, and its application to organic degradation was investigated. The RF underwater discharge was observed to be generated within the bubble at electrode surface formed by RF and plasma heating. It was shown that the sizes of the bubbles and plasmas increased as the driving frequency and the input power went up. The breakdown voltage decreased rapidly with the increase of the water conductivity and driving frequency. Comparative experiments of the UV-VIS absorbance spectra of Congo Red solution before and after discharge suggested effective degradation of the organic dye due to the active species generated during the discharge, such as .OH, .O, .H, etc. revealed by optical emission spectroscopy. The results show that higher exciting frequency and lower conduc- tivity of the solution are more effective for organic degradation. With the combination of Fourier Transform Infrared Spectroscopy （FT-IR） and Liquid Chromatography-Mass Spectrometry （LC- MS） data, one possible degradation process was proposed and the main conceivable components and structures of the products were also presented.
基金supported by 973 Program of China(No.2011CB808104)National Natural Science Foundation of China(Nos.11125526,10834008,61008010 and 60921004)Shanghai Natural Science Foundation(No.10ZR1433800)
文摘In our previous work, a plasma approach for single attosecond pulse （AP） generation was proposed. A few-cycle relativistic circularly polarized laser pulse will induce a single drastic oscillation of plasma boundary, from which high-order harmonics and furthermore an ultra-intense single AP can be generated naturally after it is reflected. Analytical model and simulations both demonstrate that the process is mostly efficient as the pulse duration is close to the plasma responding time. The effects of plasma density ramp are analyzed here, suggesting that the proposal is still quite efficient with appropriate density gradient in the ramp. At last, a combined approach is employed to obtain single AP with 30 fs incident laser. The relatively large-duration pulse is firstly shortened by a density dropping thin foil, and then reflected from an overdense plasma target. One-dimensional simulation shows that a 600 as single light pulse is generated with peak intensity of 3×10^20 W/cm^2.
基金supported in part by National Natural Science Foundation of China(Nos.10675121,10333030)
文摘The plasma density and electron temperature of a multi-source plasma system composed of several collisional inductively coupled plasma （ICP） cells were measured by a doubleprobe. The discharges of the ICP cells were shown to be independent of each other. Furthermore, the total plasma density at simultaneous multi-cell discharge was observed to be approximately equal to the summation of the plasma density when the cells discharge separately. Based on the linear summation phenomenon, it was shown that a larger area plasma with a uniform density and temperature profile could be constructed with multi-collisional ICP cells.
基金Supported by the National Key Basic Research Program of China under Grant No 2006CB806004, the National Natural Science Foundation of China under Grant Nos 10675155 and 10834008, Scientific Research Foundation for Awarder of Excellent Doctor Thesis, and President Award of Chinese Academy of Sciences （No 0801051-X00）.
文摘Two dimensional particle-in-cell simulations are taken to study the interaction of a circularly polarized laser pulse with a nano-scale micro-structured target. The protons which are doped in the rear side of the target experience the electrostatic fields caused by both the radiation pressure driven shock and the target normal sheath at the rear side of the target. A quasimonoenergetic proton bunch with central energy of about 11MeV and energy spread of ＆#8710; ε/ε about 0.18 is achieved by using a 3.45×1019 W/cm2, 66fs laser pulse. A comparison with the case of linearly polarized laser pulse and the same target condition is considered.
基金Project supported by National Natural Science Foundation of China (Grant Nos 10675155 and 10834008)the 973 Program (GrantNo 2006CB806004)Japan-Korea-China Cooperative Project on High Energy Density Sciences for Laser Fusion Energy
文摘A scheme of generating energetic ions by the interaction of an ultrahigh-intensity laser pulse and a thin solid foil is studied. The combination of the effects of radiation pressure and Coulomb explosion makes the ion acceleration more effective. The maximum ion velocity variation with time is predicted theoretically while the temporal evolution of the electrostatic field due to the Coulomb explosion is taken into consideration. Two-dimensional particle-in-cell simulations are done to verify the theory.
