A high precision laser trigger system is built up in the single test module of Primary Test Stand （PTS） facility. A fourth harmonic, with a wavelength A of 266 nm, Q-switched Nd：YAG laser was used to trigger the 5 ...A high precision laser trigger system is built up in the single test module of Primary Test Stand （PTS） facility. A fourth harmonic, with a wavelength A of 266 nm, Q-switched Nd：YAG laser was used to trigger the 5 MV multi-gap multi-channel gas switch which was filled with high pressure SF6-N2 mixture gas. The maximum deviation and the standard deviation in the jitter time of the trigger system is 4- 0.7 ns and 0.3 ns respectively. The maximum deviation and the standard deviation in the jitter time for the multi-gap multi-channel laser triggering switch is 4- 2.4 ns and 1.5 ns respectively. The curve of switch delay-time versus laser energy is obtained, which is helpful for the choice of fitting laser energy. The successful test with two lasers indicated that the design of using twenty-four lasers to trigger twenty-four switches respectively is feasible in ＂PTS＂.展开更多
A 22-stage 4 MV laser-triggered multistage multi-channel switch （LTS） was designed according to the hypothesis that the well-proportioned electrical field distribution is helpful in reducing the jitter of delay. Fie...A 22-stage 4 MV laser-triggered multistage multi-channel switch （LTS） was designed according to the hypothesis that the well-proportioned electrical field distribution is helpful in reducing the jitter of delay. Field distribution in the switch section is regulated by a metal field regulation ring and several gradient rings. In order to reduce the jitter further, a SFB/N2 mixture is chosen as the switching medium. The generalized standard deviation of the self-breakdown voltage and the deviation of the average value from the prediction is less than 4.4% and 13% respectively. Linearity of the self-breakdown voltage is better than 0.95. Triggered by a laser pulse of 35 mJ/3 ns, the delay is about 26 ns at a working voltage of 85±3% USB （Self-breakdown Voltage）. Maximum deviation of delay is less than =t=2.5 ns. Jitter is less than 1.5 ns. The delay and jitter decrease with the increase in the working ratio （the ratio of working voltage to USB）, pressure or voltage.展开更多
This paper demonstrates the triggering and guiding of the stationary high voltage （HV） discharges at 5-40kV by using plasma filaments generated by femtosecond laser pulses in air. A significant reduction of the brea...This paper demonstrates the triggering and guiding of the stationary high voltage （HV） discharges at 5-40kV by using plasma filaments generated by femtosecond laser pulses in air. A significant reduction of the breakdown voltage threshold due to the pre-ionization of the air gap by laser filamentation is observed. The discharge experiments are performed by using laser pulses with different energy from 15-60 mJ. The electron density of filaments is detected by sonography method. The influence of the electron density of laser filaments on the triggering and guiding HV discharge is experimentally investigated. The results have shown that the behaviour of plasma filaments can strongly affect the efficiency of triggering and guiding HV discharge.展开更多
Picosecond pulse radiolysis of neat tetrahydrofuran (THF) shows a fast decay of the solvated electron within 2.5ns.The decay of the solvated electron observed at 790nm is because of spur reaction.A numerical simulatio...Picosecond pulse radiolysis of neat tetrahydrofuran (THF) shows a fast decay of the solvated electron within 2.5ns.The decay of the solvated electron observed at 790nm is because of spur reaction.A numerical simulation using time dependent Smoluchowski equation containing a sink term with a distance dependent reaction rate is used to fit the pulse-probe data and shows that the geminate reaction can proceed at long distance in this low polar solvent.展开更多
There exist three synchronizing problems in the bistatic radar system that some signals of the radar receiver must be synchronized with those of the radar transmitter. Several methods realizing data transmission, whic...There exist three synchronizing problems in the bistatic radar system that some signals of the radar receiver must be synchronized with those of the radar transmitter. Several methods realizing data transmission, which are used to complete the synchronization existing in the bistatic radar system, are described. Then a new idea is brought forward that employs space laser communication in the bistatic radar system to realize its data transmission. The theoretic analysis of the idea's usability and its merits are discussed in details. Finally the latest development of space laser communication is introduced, and the utility of the idea is pointed out further.展开更多
基金supported by National Natural Science Foundation of China (No.10574096)the Research Fund for the Doctoral Program of Higher Education of China (No.20050610010)
文摘A high precision laser trigger system is built up in the single test module of Primary Test Stand （PTS） facility. A fourth harmonic, with a wavelength A of 266 nm, Q-switched Nd：YAG laser was used to trigger the 5 MV multi-gap multi-channel gas switch which was filled with high pressure SF6-N2 mixture gas. The maximum deviation and the standard deviation in the jitter time of the trigger system is 4- 0.7 ns and 0.3 ns respectively. The maximum deviation and the standard deviation in the jitter time for the multi-gap multi-channel laser triggering switch is 4- 2.4 ns and 1.5 ns respectively. The curve of switch delay-time versus laser energy is obtained, which is helpful for the choice of fitting laser energy. The successful test with two lasers indicated that the design of using twenty-four lasers to trigger twenty-four switches respectively is feasible in ＂PTS＂.
文摘A 22-stage 4 MV laser-triggered multistage multi-channel switch （LTS） was designed according to the hypothesis that the well-proportioned electrical field distribution is helpful in reducing the jitter of delay. Field distribution in the switch section is regulated by a metal field regulation ring and several gradient rings. In order to reduce the jitter further, a SFB/N2 mixture is chosen as the switching medium. The generalized standard deviation of the self-breakdown voltage and the deviation of the average value from the prediction is less than 4.4% and 13% respectively. Linearity of the self-breakdown voltage is better than 0.95. Triggered by a laser pulse of 35 mJ/3 ns, the delay is about 26 ns at a working voltage of 85±3% USB （Self-breakdown Voltage）. Maximum deviation of delay is less than =t=2.5 ns. Jitter is less than 1.5 ns. The delay and jitter decrease with the increase in the working ratio （the ratio of working voltage to USB）, pressure or voltage.
基金supported by the National Natural Science Foundation of China (Grant Nos 10734130,10634020,60621063)National Basic Research Programme of China (Gant No 2007CB815101)
文摘This paper demonstrates the triggering and guiding of the stationary high voltage （HV） discharges at 5-40kV by using plasma filaments generated by femtosecond laser pulses in air. A significant reduction of the breakdown voltage threshold due to the pre-ionization of the air gap by laser filamentation is observed. The discharge experiments are performed by using laser pulses with different energy from 15-60 mJ. The electron density of filaments is detected by sonography method. The influence of the electron density of laser filaments on the triggering and guiding HV discharge is experimentally investigated. The results have shown that the behaviour of plasma filaments can strongly affect the efficiency of triggering and guiding HV discharge.
文摘Picosecond pulse radiolysis of neat tetrahydrofuran (THF) shows a fast decay of the solvated electron within 2.5ns.The decay of the solvated electron observed at 790nm is because of spur reaction.A numerical simulation using time dependent Smoluchowski equation containing a sink term with a distance dependent reaction rate is used to fit the pulse-probe data and shows that the geminate reaction can proceed at long distance in this low polar solvent.
文摘There exist three synchronizing problems in the bistatic radar system that some signals of the radar receiver must be synchronized with those of the radar transmitter. Several methods realizing data transmission, which are used to complete the synchronization existing in the bistatic radar system, are described. Then a new idea is brought forward that employs space laser communication in the bistatic radar system to realize its data transmission. The theoretic analysis of the idea's usability and its merits are discussed in details. Finally the latest development of space laser communication is introduced, and the utility of the idea is pointed out further.
