In this paper, a one-dimensional discharge model is employed to study multi-pulse phenomena in Ar dielectric barrier discharge （DBD） under atmospheric pressure. The finiteelement method is employed to solve the mode...In this paper, a one-dimensional discharge model is employed to study multi-pulse phenomena in Ar dielectric barrier discharge （DBD） under atmospheric pressure. The finiteelement method is employed to solve the model. The influences of applied voltage amplitude and frequency as well as gas gap distance on the variation of multi discharge pulses are investigated and discussed. The simulation results show that, both the intensity of discharge current and the number of discharge pulses increase with the amplitude of applied voltage, and narrower gas gap is more favorable for the formation of multi pulses. It is revealed that Ar DBDs behave in glow discharge mode when the applied voltage and gas gap distance vary from 2 kV to 6 kV and from 1 mm to 3 mm, respectively. With the frequency decreasing from 250 Hz to 125 Hz, the intensity of discharge current weakens and the number of discharge pulses increases, and the discharges behave in the typical Townsend discharge mode.展开更多
We report on a novel architecture to suppress the multi-pulse formation in an all-polarization-maintaining figure-9 erbium-doped fiber laser under high pump power. A 2×2 fiber coupler is introduced into the phase...We report on a novel architecture to suppress the multi-pulse formation in an all-polarization-maintaining figure-9 erbium-doped fiber laser under high pump power. A 2×2 fiber coupler is introduced into the phase-biased nonlinear amplifying loop mirror to extract part of intracavity laser power as a laser output, and the dependence of output couple ratio of fiber coupler on the mode-locking state is experimentally investigated. The intracavity nonlinear effect is mitigated by lowering the intracavity laser power, which is conducive to avoiding the multi-pulse formation. In the meantime, the loss-imbalance induced by fiber coupler is helpful in improving the self-starting ability. With the proposed laser structure,the multiple pulse formation can be suppressed and high power single pulse train can be obtained. The laser emits three pulse trains which is convenient for some applications. Finally, the output power values of three ports are 5.3 m W, 51.3 m W,and 13.2 m W, respectively. The total single pulse output power is 69.8 m W, which is more than 10 times the result without OC2. The total slope efficiency is about 10.1%. The repetition rate of three pulse trains is 21.17 MHz, and the pulse widths are 2.8 ps, 2.63 ps, and 6.66 ps, respectively.展开更多
The velvet electron emission characteristics and beams＇ brightness are investigated with a multi-pulsed mode. The results indicate that in the multi-pulsed mode the velvet emission is not uniform and the periphery em...The velvet electron emission characteristics and beams＇ brightness are investigated with a multi-pulsed mode. The results indicate that in the multi-pulsed mode the velvet emission is not uniform and the periphery emission is much stronger than that from the centre. The periphery emission contributes much more to the formation of the cathode plasma than the centre emission, which leads to diode impendence breakdown. The relationship between the cathode plasma expansion and the initial emittance of the cathode is deduced to describe the characteristics of the multi-pulsed vacuum diode. The emittance of the multi-pulsed beams is measured to be less than 1000mm·mrad. The brightness of the electron beams is better than 1× 10^8A/（m·rad）2.展开更多
The ε-Fe3N-based magnetic lubricant which is stable and high saturation magnetization has been prepared by a homemade DBD device under the atmospheric pressure. The results show that the NH3 flow rate, the applied pe...The ε-Fe3N-based magnetic lubricant which is stable and high saturation magnetization has been prepared by a homemade DBD device under the atmospheric pressure. The results show that the NH3 flow rate, the applied peak-to-peak voltage and the mass ratio of surfactant and carrier lubricant have important effects on the phase structure, the magnetic properties, the size of ferroparticles and the stability of the ε-Fe3N-based magnetic lubricant. TEM images show the e-Fe3N ferroparticles are dispersed in the carrier lubricant homogeneously, and the cluster phenomenon is not observed. The stable e-Fe3N-based magnetic lubricant with the saturation magnetization of 50.11 mT and the mean ferroparticle size of 11 nm is prepared successfully. The main particles of the atmospheric-pressure Ar/NH3/Fe（CO）5 DBD plasma are NH, N, N＋, Fe, N2, Ar, Ha, and CO; NH is a decomposition product of NH3. Fe and N active radicals are two elementary species in the preparation of the c-Fe3N-based magnetic lubricant in the atmospheric-pressure DBD plasma. There are two discharge modes for DBD plasma, namely, multi-pulse APGD and filamentary discharge. By increasing the applied peak-to-peak voltage from 4600 to 7800 V, the discharge mode is changed from single-pulse APGD with filamentary discharge to two-pulse APGD with filamentary discharge, and the Lissajous figure also converts from a quadrilateral with one step to two steps on the right-hand side.展开更多
基金supported in part by China Foundation for the Author of National Excellent Doctoral Dissertation(No.200338)Fundamental Research Funds for the Central Universities of China(No.xjj20100160)
文摘In this paper, a one-dimensional discharge model is employed to study multi-pulse phenomena in Ar dielectric barrier discharge （DBD） under atmospheric pressure. The finiteelement method is employed to solve the model. The influences of applied voltage amplitude and frequency as well as gas gap distance on the variation of multi discharge pulses are investigated and discussed. The simulation results show that, both the intensity of discharge current and the number of discharge pulses increase with the amplitude of applied voltage, and narrower gas gap is more favorable for the formation of multi pulses. It is revealed that Ar DBDs behave in glow discharge mode when the applied voltage and gas gap distance vary from 2 kV to 6 kV and from 1 mm to 3 mm, respectively. With the frequency decreasing from 250 Hz to 125 Hz, the intensity of discharge current weakens and the number of discharge pulses increases, and the discharges behave in the typical Townsend discharge mode.
基金Project supported by the National Natural Science Foundation of China(Grant No.51905528)the Key Research Project of Bureau of Frontier Sciences and Education+1 种基金Chinese Academy of Sciences(Grant No.QYZDY-SSW-JSC008)the National Key Research and Development Project,China(Grant Nos.2019YFB2005600 and 2018YFB2003403)。
文摘We report on a novel architecture to suppress the multi-pulse formation in an all-polarization-maintaining figure-9 erbium-doped fiber laser under high pump power. A 2×2 fiber coupler is introduced into the phase-biased nonlinear amplifying loop mirror to extract part of intracavity laser power as a laser output, and the dependence of output couple ratio of fiber coupler on the mode-locking state is experimentally investigated. The intracavity nonlinear effect is mitigated by lowering the intracavity laser power, which is conducive to avoiding the multi-pulse formation. In the meantime, the loss-imbalance induced by fiber coupler is helpful in improving the self-starting ability. With the proposed laser structure,the multiple pulse formation can be suppressed and high power single pulse train can be obtained. The laser emits three pulse trains which is convenient for some applications. Finally, the output power values of three ports are 5.3 m W, 51.3 m W,and 13.2 m W, respectively. The total single pulse output power is 69.8 m W, which is more than 10 times the result without OC2. The total slope efficiency is about 10.1%. The repetition rate of three pulse trains is 21.17 MHz, and the pulse widths are 2.8 ps, 2.63 ps, and 6.66 ps, respectively.
文摘The velvet electron emission characteristics and beams＇ brightness are investigated with a multi-pulsed mode. The results indicate that in the multi-pulsed mode the velvet emission is not uniform and the periphery emission is much stronger than that from the centre. The periphery emission contributes much more to the formation of the cathode plasma than the centre emission, which leads to diode impendence breakdown. The relationship between the cathode plasma expansion and the initial emittance of the cathode is deduced to describe the characteristics of the multi-pulsed vacuum diode. The emittance of the multi-pulsed beams is measured to be less than 1000mm·mrad. The brightness of the electron beams is better than 1× 10^8A/（m·rad）2.
基金supported by National Natural Science Foundation of China (Grant Nos. 11605020 and 21673026)by the National Natural Science Foundation of Liaoning Province, China (Grant No. 2015020585)
文摘The ε-Fe3N-based magnetic lubricant which is stable and high saturation magnetization has been prepared by a homemade DBD device under the atmospheric pressure. The results show that the NH3 flow rate, the applied peak-to-peak voltage and the mass ratio of surfactant and carrier lubricant have important effects on the phase structure, the magnetic properties, the size of ferroparticles and the stability of the ε-Fe3N-based magnetic lubricant. TEM images show the e-Fe3N ferroparticles are dispersed in the carrier lubricant homogeneously, and the cluster phenomenon is not observed. The stable e-Fe3N-based magnetic lubricant with the saturation magnetization of 50.11 mT and the mean ferroparticle size of 11 nm is prepared successfully. The main particles of the atmospheric-pressure Ar/NH3/Fe（CO）5 DBD plasma are NH, N, N＋, Fe, N2, Ar, Ha, and CO; NH is a decomposition product of NH3. Fe and N active radicals are two elementary species in the preparation of the c-Fe3N-based magnetic lubricant in the atmospheric-pressure DBD plasma. There are two discharge modes for DBD plasma, namely, multi-pulse APGD and filamentary discharge. By increasing the applied peak-to-peak voltage from 4600 to 7800 V, the discharge mode is changed from single-pulse APGD with filamentary discharge to two-pulse APGD with filamentary discharge, and the Lissajous figure also converts from a quadrilateral with one step to two steps on the right-hand side.
