The properties of a helium atmospheric-pressure plasma jet（APPJ）are diagnosed with a dual assisted grounded electrode dielectric barrier discharge device.In the glow discharge,we captured the current waveforms at th...The properties of a helium atmospheric-pressure plasma jet（APPJ）are diagnosed with a dual assisted grounded electrode dielectric barrier discharge device.In the glow discharge,we captured the current waveforms at the positions of the three grounded rings.From the current waveforms,the time delay between the adjacent positions of the rings is employed to calculate the plasma bullet velocity of the helium APPJ.Moreover,the electron density is deduced from a model combining with the time delay and current intensity,which is about 10^（11）cm^（-3）.In addition,The ion-neutral particles collision frequency in the radial direction is calculated from the current phase difference between two rings,which is on the order of 10~7 Hz.The results are helpful for understanding the basic properties of APPJs.展开更多
Plasma photonic crystals composed of periodic plasma and dielectric materials have attracted considerable attention because of their tunable photonic band gaps,but only their band structures or negative refractive ind...Plasma photonic crystals composed of periodic plasma and dielectric materials have attracted considerable attention because of their tunable photonic band gaps,but only their band structures or negative refractive index properties have been addressed in previous works.In this paper,through studying the transmission and reflection characteristics of two types of twodimensional plasma photonic crystals,it is found that plasma photonic crystals play an important role in absorbing waves,and they show broader band and higher amplitude absorption characteristics than bulk plasmas.Also,the absorption of plasma photonic crystals can be tuned via plasma parameters;varying the collision frequency can make the bandwidth and amplitude tunable,but cannot change the central frequency,whereas varying the plasma frequency would control both the location and the amplitude of the absorbers.These features of plasma photonic crystals have potential for terahertz tunable absorber applications.展开更多
基金supported by National Natural Science Foundation of China(No.11105093)the Technological Project of Shenzhen,China(No.JC201005280485A)the Planned S&T Program of Shenzhen,China(No.JC201105170703A)
文摘The properties of a helium atmospheric-pressure plasma jet（APPJ）are diagnosed with a dual assisted grounded electrode dielectric barrier discharge device.In the glow discharge,we captured the current waveforms at the positions of the three grounded rings.From the current waveforms,the time delay between the adjacent positions of the rings is employed to calculate the plasma bullet velocity of the helium APPJ.Moreover,the electron density is deduced from a model combining with the time delay and current intensity,which is about 10^（11）cm^（-3）.In addition,The ion-neutral particles collision frequency in the radial direction is calculated from the current phase difference between two rings,which is on the order of 10~7 Hz.The results are helpful for understanding the basic properties of APPJs.
基金supported by National Natural Science Foundation of China(Nos.61107030,11174280,60990323 and 60990320)the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province(No.BS2010CL025)the China Postdoctoral Science Foundation
文摘Plasma photonic crystals composed of periodic plasma and dielectric materials have attracted considerable attention because of their tunable photonic band gaps,but only their band structures or negative refractive index properties have been addressed in previous works.In this paper,through studying the transmission and reflection characteristics of two types of twodimensional plasma photonic crystals,it is found that plasma photonic crystals play an important role in absorbing waves,and they show broader band and higher amplitude absorption characteristics than bulk plasmas.Also,the absorption of plasma photonic crystals can be tuned via plasma parameters;varying the collision frequency can make the bandwidth and amplitude tunable,but cannot change the central frequency,whereas varying the plasma frequency would control both the location and the amplitude of the absorbers.These features of plasma photonic crystals have potential for terahertz tunable absorber applications.
