scholarly journals Investigation of Nonthermal Plasma Jet Excitation Mode and Optical Assessment of Its Electron Concentration

2021 ◽  
Vol 11 (19) ◽  
pp. 9203
Author(s):  
Anton S. Ivankov ◽  
Anastasia M. Kozhevnikova ◽  
Dmitry V. Schitz ◽  
Igor V. Alekseenko
Keyword(s):  
Electron Concentration ◽  
Plasma Parameter ◽  
Short Pulse ◽  
Nonthermal Plasma ◽  
Plasma Jet ◽  
Pulse Mode ◽  
Pulse Excitation ◽  
Gas Temperature ◽  
Helium Flow ◽  
Set Up

The results of a study of a plasma jet of atmospheric-pressure helium driven by a capacitive discharge using sine and pulsed modes of excitation are presented. The homogeneous discharge of a multi-channel plasma jet at gas temperature of 34 °C and helium flow rate of 0.5 L/min was achieved with short pulse excitation. A digital holography method is proposed to estimate a basic plasma parameter, i.e., its electron concentration. An automated digital holographic interferometry set-up for the observation and study of a nonthermal plasma jet in a pulse mode is developed and described. The synchronization features of recording devices with the generation of plasma pulses are considered. The electron concentration of the plasma jet is also estimated. The disadvantages of the proposed technique and its further application are discussed.

Threshold current characteristics of GaAs lasers under short pulse excitation

1984 ◽  
Vol 20 (2) ◽  
pp. 63 ◽  
Author(s):  
N.A. Olsson ◽  
N.K. Dutta ◽  
W.T. Tsang ◽  
R.A. Logan
Keyword(s):  
Short Pulse ◽  
Threshold Current ◽  
Pulse Excitation ◽  
Current Characteristics

scholarly journals Mind the gap – Part 1: Accurately locating warm marine boundary layer clouds and precipitation using spaceborne radars

2020 ◽  
Vol 13 (5) ◽  
pp. 2363-2379 ◽  
Author(s):  
Katia Lamer ◽  
Pavlos Kollias ◽  
Alessandro Battaglia ◽  
Simon Preval
Keyword(s):  
Boundary Layer ◽  
Cloud Cover ◽  
Marine Boundary Layer ◽  
Short Pulse ◽  
Pulse Mode ◽  
Cloud Base ◽  
Boundary Layer Clouds ◽  
Highly Sensitive ◽  
Eastern North Atlantic ◽  
Long Pulse

Abstract. Ground-based radar observations show that, over the eastern North Atlantic, 50 % of warm marine boundary layer (WMBL) hydrometeors occur below 1.2 km and have reflectivities of < −17 dBZ, thus making their detection from space susceptible to the extent of surface clutter and radar sensitivity. Surface clutter limits the ability of the CloudSat cloud profiling radar (CPR) to observe the true cloud base in ∼52 % of the cloudy columns it detects and true virga base in ∼80 %, meaning the CloudSat CPR often provides an incomplete view of even the clouds it does detect. Using forward simulations, we determine that a 250 m resolution radar would most accurately capture the boundaries of WMBL clouds and precipitation; that being said, because of sensitivity limitations, such a radar would suffer from cloud cover biases similar to those of the CloudSat CPR. Observations and forward simulations indicate that the CloudSat CPR fails to detect 29 %–43 % of the cloudy columns detected by ground-based sensors. Out of all configurations tested, the 7 dB more sensitive EarthCARE CPR performs best (only missing 9.0 % of cloudy columns) indicating that improving radar sensitivity is more important than decreasing the vertical extent of surface clutter for measuring cloud cover. However, because 50 % of WMBL systems are thinner than 400 m, they tend to be artificially stretched by long sensitive radar pulses, hence the EarthCARE CPR overestimation of cloud top height and hydrometeor fraction. Thus, it is recommended that the next generation of space-borne radars targeting WMBL science should operate interlaced pulse modes including both a highly sensitive long-pulse mode and a less sensitive but clutter-limiting short-pulse mode.

Optical Study of Localized and Delocalized States in GaAsN/GaAs

2003 ◽  
Vol 798 ◽  
Author(s):  
Z. Y. Xu ◽  
X. D. Luo ◽  
X. D. Yang ◽  
P. H. Tan ◽  
C. L. Yang ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Rapid Thermal Annealing ◽  
Short Pulse ◽  
Selective Excitation ◽  
Excitation Power ◽  
Pulse Excitation ◽  
Optical Study ◽  
Time Resolved ◽  
Exciton Localization ◽  
Time Resolved Photoluminescence

ABSTRACTTaking advantages of short pulse excitation and time-resolved photoluminescence (PL), we have studied the exciton localization effect in a number of GaAsN alloys and GaAsN/GaAs quantum wells (QWs). In the PL spectra, an extra transition located at the higher energy side of the commonly reported N-related emissions is observed. By measuring PL dependence on temperature and excitation power along with PL dynamics study, the new PL peak has been identified as a transition of the band edge-related recombination in dilute GaAsN alloy and delocalized transition in QWs. Using selective excitation PL we further attribute the localized emission in QWs to the excitons localized at the GaAsN/GaAs interfaces. This interface-related exciton localization could be greatly reduced by a rapid thermal annealing.

scholarly journals Effects of Er:YAG Laser on Mineral Content of Sound Dentin in Primary Teeth

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Cigdem Guler ◽  
Meral Arslan Malkoc ◽  
Veli Alper Gorgen ◽  
Erhan Dilber ◽  
Mehmet Bulbul
Keyword(s):  
Surface Roughness ◽  
Mineral Content ◽  
Primary Teeth ◽  
Er:Yag Laser ◽  
Short Pulse ◽  
Pulse Mode ◽  
Emission Spectrometry ◽  
Control Group ◽  
Group A ◽  
Group B

The aim of the present study was to evaluate the mineral content of sound dentin in primary teeth prepared using an Er:YAG laser at two different power settings. Thirty-six primary second molars were used in this study. Three dentin slabs were obtained from each tooth, and the slabs were randomly divided into three groups: Group A, control; Group B, Er:YAG laser at 3.5 W, 175 mJ, and 20 Hz, short pulse mode; and Group C, Er:YAG laser at 4 W, 200 mJ, and 20 Hz, medium-short pulse mode. One dentin slab per group was used to evaluate the dentinal morphology and surface roughness values using SEM and profilometer, respectively. Mineral content in the dentin slabs were calculated by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The data were analyzed by one-way analysis of variance and Tukey’s HSD tests. No significant differences in Ca, K, Mg, Na, and P levels or Ca/P ratio were found among the groups(P>0.05). SEM micrographs showed that surface irregularities increased with a higher power setting. The surface roughness after laser treatment in Group B and Group C was found to be similar, unlike Group A.

scholarly journals Modeling, Simulation and Uncertain Optimization of the Gun Engraving System

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 398
Author(s):  
Tong Xin ◽  
Guolai Yang ◽  
Fengjie Xu ◽  
Quanzhao Sun ◽  
Alexandi Minak
Keyword(s):  
Performance Evaluation ◽  
Optimal Design ◽  
Resistance Force ◽  
Gas Temperature ◽  
Evaluation Indexes ◽  
Uncertain Optimization ◽  
Design Variables ◽  
Set Up ◽  
Rotating Band ◽  
Percent Decrease

The system designed to accomplish the engraving process of a rotating band projectile is called the gun engraving system. To obtain higher performance, the optimal design of the size parameters of the gun engraving system was carried out. First, a fluid–solid coupling computational model of the gun engraving system was built and validated by the gun launch experiment. Subsequently, three mathematic variable values, like performance evaluation indexes, were obtained. Second, a sensitivity analysis was performed, and four high-influence size parameters were selected as design variables. Finally, an optimization model based on the affine arithmetic was set up and solved, and then the optimized intervals of performance evaluation indexes were obtained. After the optimal design, the percent decrease of the maximum engraving resistance force ranged from 6.34% to 18.24%; the percent decrease of the maximum propellant gas temperature ranged from 1.91% to 7.45%; the percent increase of minimum pressure wave of the propellant gas ranged from 0.12% to 0.36%.

Control of reactive oxygen and nitrogen species production in liquid by nonthermal plasma jet with controlled surrounding gas

2016 ◽  
Vol 56 (1S) ◽  
pp. 01AC06 ◽  
Author(s):  
Taiki Ito ◽  
Giichiro Uchida ◽  
Atsushi Nakajima ◽  
Kosuke Takenaka ◽  
Yuichi Setsuhara
Keyword(s):  
Reactive Oxygen ◽  
Nonthermal Plasma ◽  
Plasma Jet ◽  
Nitrogen Species ◽  
Species Production

Modelling Flue Gas Desulfurization Using Pyrolusite Pulp in a Jet Bubbling Reactor

2009 ◽  
Vol 610-613 ◽  
pp. 85-96 ◽  
Author(s):  
Jing Dong Zhao ◽  
Shi Jun Su ◽  
Nan Shan Ai ◽  
Xiao Fan Zhu
Keyword(s):  
Flue Gas ◽  
Ph Value ◽  
Scale Up ◽  
Absorption Efficiency ◽  
Flue Gas Desulfurization ◽  
Process Conditions ◽  
Gas Temperature ◽  
Transfer Coefficients ◽  
Set Up ◽  
So2 Absorption

A mathematical model for flue gas desulfurization using pyrolusite pulp in jet bubbling reactor (JBR) was described. Firstly, based on the concept of two stages mass balance with chemical reaction, two models were set up, for jet bubbling zone and rising bubble zone, respectively, according to the construction of JBR. The models consist of two coupling differential equations and were solved simultaneously by integral and separation of the variables. Then the SO2 absorption efficiency expression was developed, considering the great discrepancy existing between the gas-side mass transfer coefficients of the jet bubbling zone and gas bubble rising zone. The final expression associates SO2 absorption efficiency with process conditions and JBR structure parameters, which can give some instruction and guidance for the study of reactor operation process. Predicted results from the theoretical model, including effect of pH value of the pulp, flue gas temperature and inlet SO2 concentration of flue gas on SO2 absorption efficiency, were found to be in good agreement with experimental data obtained in a jet bubbling reactor. The model provides a basis for the process scale up and operating guide.

Boundary Layer Temperature Profile in Diamond CVD System Using Laser-Induced Fluorescence

1995 ◽  
Vol 416 ◽  
Author(s):  
Qingyu Wang ◽  
Jon L. Lindsay ◽  
David L. Hofeldt
Keyword(s):  
Boundary Layer ◽  
Temperature Profile ◽  
Population Distribution ◽  
Substrate Surface ◽  
Plasma Jet ◽  
Laser Induced Fluorescence ◽  
Diamond Growth ◽  
Oh Radicals ◽  
Measured Temperature ◽  
Gas Temperature

ABSTRACTThe gas temperature of a radio-frequency thermal plasma has been measured by laser-induced fluorescence along the axis of the plasma jet near the substrate surface. The temperature was determined from the rotational population distribution of OH radicals. From the measured temperature profile, the freestream temperature was found to be about 3400 K and the boundary layer thickness was determined to be about 1 mm. A numerical model including carbonhydrogen- argon kinetics was used to predict species concentrations near the surface of the substrate. The results indicate that all CHa radical concentrations increase with freestream temperature for temperatures between 2500-4000 K. Of the C1 radicals, methyl has the highest concentration in this range in our system, which is consistent with other reports that methyl is an important diamond growth species.

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