Extreme ultraviolet spectral characteristic analysis of highly charged ions in laserproduced Cu plasmas

This paper reports the results of spectral measurements and a theoretical analysis of the temporal and spatial evolution of laser-produced Cu plasma in vacuum in the range of 8–14 nm.The time dependence of the extreme ultraviolet band spectrum at different positions near the target surface was obtained and found to be dominated by three broad-band features.The 3p and 3d excitations of Cu5+–Cu9+ions were calculated using the Hartree–Fock theory with configuration interactions.The characteristics of the spectral line distribution for the 3p–nd and 3d–nf transition arrays were analyzed.Based on the steady-state collisional radiation model and the normalized Boltzmann distribution,the complex spectral structure in the band of 13–14 nm is accurately explained through consistency comparisons and benchmarking between the experimental and theoretical simulation spectra,demonstrating that the structure mainly stems from the overlapping contribution of the 3d–4f and 3p–3d transition arrays for the Cu5+–Cu9+ions.These results may help in studying the radiation characteristics of isoelectronic series highly-charged ions involving the 3d excitation process.

Electrical and Optical Characteristics of Electrodeless Lamp

In order to study the methods to enhance the efficacy of electrodeless lamp,volt-ampere characteristics,illuminance and emission spectrum have been investigated in home-built electrodeless lamp experimental system with an electrodeless lamp in shape like QL 85 lamp.The results show that lamp current increases as lamp voltage increases in non-discharge,the current decreases first and then increases as the voltage increases in discharge.The illuminance of electrodeless lamp increases linearly with discharge power increasing,and it decreases linearly with power decreasing.The emission spectrum is different for different bulb and lighting time.The spectrum of Ar 811.5 nm,76.5 nm,750.4 nm and Hg 313.2 nm decrease with lighting time.While the intensity of Hg 407.8 nm increases with lighting time.

Experimental investigation on the plasma morphology of ablative pulsed plasma thruster with tongue-shaped and flared electrodes

Ablative pulsed plasma thrusters(APPTs)are considered as an attractive propulsion option for station-keeping and drag makeup purposes for mass-and power-limited satellites.In order to understand the physical mechanism of APPTs,high-speed camera and optical emission spectroscopy are utilized to investigate the plasma characteristics including the spatial distribution and composition between the electrodes.The plume images and spectra at different times and positions are experimentally recorded,and the spatial distribution,composition,and trajectory of plasmas can be concluded through analyzing them.With the increase of the distance from the ablation surface,two clusters of plasmas near the anode and cathode meet downstream,and the species and density of plasmas tend to be uniform.

Spatiotemporal characteristics of nanosecond pulsed discharge in an extremely asymmetric electric field at atmospheric pressure

In this paper,high resolution temporal-spatial diagnostics are employed to research the optical characteristics of nanosecond pulsed dielectric barrier discharge in needle-plate electrode configuration.Temporal-spatial distributions of discharge images,the emission intensities of optical emission spectra,and plasma vibrational and rotational temperatures are investigated.By analyzing the evolution of vibrational and rotational temperatures in space and time dimensions,the energy distribution and energy transfer process in plasma are also discussed.It is found that a diffuse structure with high density plasma concentrated in the region near the needle tip can be presented in nanosecond pulsed discharge,and an obvious energy transfer from electronic energy to vibration energy can be observed in each discharge pulse.

Controllable optical emission wavelength in all-inorganic halide perovskite alloy microplates grown by two-step chemical vapor deposition

All-inorganic halide perovskites(IHP),CsPbX_(3)(X=Cl,Br,I)exhibiting efficient optical emissions within the spectral range of 410 to 730 nm are potential candidates for many optoelectronic devices.Anion alloying of these IHPs is expected to achieve tunable emission wavelength covering the entire visible spectrum.Here,we developed a two-step chemical vapor deposition(CVD)process for growing quaternary IHP CsPbX_(3)(X=Cl/Br and Br/I)alloys.By exploiting the fast diffusion of halide anions in IHPs,the alloy composition can be precisely controlled by the growth time of the respective layers once the growth of the individual ternary IHP is optimized.Hence complexities in the multi-parameter optimization in the conventional CVD growth of quaternary alloys can be mitigated.Using this process,we synthesized single crystalline,homogeneous and thermally stable CsPbCl3_((1−X))Br_(3x)and CsPbBr3_((1−X))I_(3x)perovskites alloy microplates and demonstrated continuously tunable emission covering the spectrum from 428 to 715 nm by varying the halide compositions in the alloys.These alloy microplates also exhibit room temperature amplified spontaneous emissions(ASE)along with strong photonic discharges from the microplate’s edges and hence are potentially useful as a gain medium as well as optical cavities for emissions with wavelengths covering the visible spectrum.

Nonreciprocal transition between two indirectly coupled energy levels

We propose a theoretical scheme to realize nonreciprocal transition between two energy levels that can not coupled directly.Suppose they are coupled indirectly by two auxiliary levels with a cyclic four-level configuration,and the four transitions in the cyclic configuration are controlled by external fields.The indirectly transition become nonreciprocal when the time reversal symmetry of the system is broken by the synthetic magnetic flux,i.e.,the total phase of the external driving fields through the cyclic four-level configuration.The nonreciprocal transition can be identified by the elimination of a spectral line in the spontaneous emission spectrum.Our work introduces a feasible way to observe nonreciprocal transition in a wide range of multi-level systems,including natural atoms or ions with parity symmetry.