The physical mechanism of gain motivation is the main theoretical bottleneck that restricts the signal-to-noise ratio(SNR)and results in a mono-merit implementation for the existing stimulated Brillouin scattering-bas...The physical mechanism of gain motivation is the main theoretical bottleneck that restricts the signal-to-noise ratio(SNR)and results in a mono-merit implementation for the existing stimulated Brillouin scattering-based fiber sensors.A phase-chaos laser(PCL)is proposed and introduced in the Brillouin optical correlation domain analysis(BOCDA)scheme to promote the SNR and achieve a high-accuracy measurement.The PCL characteristics are presented,and a theoretical model of chaos gain accumulation and extraction is perfected.Then,the simulation results reveal that the SNR is improved by 5.56 dB,and the signal-to-background noise ratio(SBR)of the Brillouin gain spectrum(BGS)is promoted by 8.28 dB with a 100-km sensing distance.Further,the PCL is experimentally generated.In the proof-of-concept experiment,the accuracy of the Brillouin frequency shift is upgraded to 0.64 MHz,and the SBR of BGS is improved by 10.77 dB.The PCL provides a new research direction for optical chaos,and the PCL-BOCDA showcases a promising future for optimal-merit-coupling sensing and its application.展开更多
Gliding arc is a mostly used non-equilibrium plasma generation method whose characteristic is affected by the backbreakdown phenomenon.Mode transition induced by back-breakdown of the gliding arc is studied in this wo...Gliding arc is a mostly used non-equilibrium plasma generation method whose characteristic is affected by the backbreakdown phenomenon.Mode transition induced by back-breakdown of the gliding arc is studied in this work and effects of gas flow rate,applied voltage,electrode parameters on mode transition were studied.Experimental results show that there are two typical modes during the development of the gliding arc.Mode A comprises periodicitical development of the arc from the minimum gap breakdown to the longest extinguishment,while the arc in mode B continues to produce a back-breakdown at the ends of the electrodes.As the flow rate descends,the gliding arc gradually changes from mode A to B.It is the decrease of the arc velocity caused by lower flow rate leads to the occurrence of back-breakdown,which generates mode B.Smaller electrode opening angle,shorter length and wider minimum gap reduce the gliding speed,so that arc is more likely to enter mode B.As the applied voltage is increased,enhancing of the electric field strength on the breakdown path of the back-breakdown and thickening of the arc's diameter allow the gliding arc to enter mode B at a higher arc speed.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2023YFF0715700)the National Natural Science Foundation of China(Grant Nos.62205233,U23A20375,and 62075151)+1 种基金the Fundamental Research Program of Shanxi Province(Grant No.202103021223041)the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(Grant No.2022SX-AT002).
文摘The physical mechanism of gain motivation is the main theoretical bottleneck that restricts the signal-to-noise ratio(SNR)and results in a mono-merit implementation for the existing stimulated Brillouin scattering-based fiber sensors.A phase-chaos laser(PCL)is proposed and introduced in the Brillouin optical correlation domain analysis(BOCDA)scheme to promote the SNR and achieve a high-accuracy measurement.The PCL characteristics are presented,and a theoretical model of chaos gain accumulation and extraction is perfected.Then,the simulation results reveal that the SNR is improved by 5.56 dB,and the signal-to-background noise ratio(SBR)of the Brillouin gain spectrum(BGS)is promoted by 8.28 dB with a 100-km sensing distance.Further,the PCL is experimentally generated.In the proof-of-concept experiment,the accuracy of the Brillouin frequency shift is upgraded to 0.64 MHz,and the SBR of BGS is improved by 10.77 dB.The PCL provides a new research direction for optical chaos,and the PCL-BOCDA showcases a promising future for optimal-merit-coupling sensing and its application.
基金the National Natural Science Foundation of China under grant no.51677105 and Shenzhen Science,Technology&Innovation Commission(SZSTI)Fund under grant no.JCYJ20180508152057527.
文摘Gliding arc is a mostly used non-equilibrium plasma generation method whose characteristic is affected by the backbreakdown phenomenon.Mode transition induced by back-breakdown of the gliding arc is studied in this work and effects of gas flow rate,applied voltage,electrode parameters on mode transition were studied.Experimental results show that there are two typical modes during the development of the gliding arc.Mode A comprises periodicitical development of the arc from the minimum gap breakdown to the longest extinguishment,while the arc in mode B continues to produce a back-breakdown at the ends of the electrodes.As the flow rate descends,the gliding arc gradually changes from mode A to B.It is the decrease of the arc velocity caused by lower flow rate leads to the occurrence of back-breakdown,which generates mode B.Smaller electrode opening angle,shorter length and wider minimum gap reduce the gliding speed,so that arc is more likely to enter mode B.As the applied voltage is increased,enhancing of the electric field strength on the breakdown path of the back-breakdown and thickening of the arc's diameter allow the gliding arc to enter mode B at a higher arc speed.
