Spatiotemporal control of femtosecond laser filament-triggered discharge and its application in diagnosing gas flow fields

Author(s):  
Zhifeng Zhu ◽  
Bo Li ◽  
Qiang Gao ◽  
Jiajian Zhu ◽  
Zhongshan Li

Abstract Precise control of the discharge in space and time is of great significance for better applications of discharge plasma. Here, we used a femtosecond laser filament to trigger and guide a high-voltage DC pulse discharge to achieve spatiotemporal control of the discharge plasma. In space, the discharge plasma is distributed strictly along the channel generated by the femtosecond laser filament. The breakdown voltage threshold is reduced, and the discharge length is extended. In time, the electrical parameters such as the electrode voltage and the electrode gap affect discharge delay time and jitter. By optimizing the parameters, we can achieve sub-nanosecond jitter of the discharge. Based on the spatiotemporal control of the discharge, we applied filament-triggered discharge for one-dimensional composition measurements of the gas flow field. Besides, the technique shows great potential in studying the spatiotemporal evolution of discharge plasma.

2019 ◽  
Vol 13 (27) ◽  
pp. 76-82
Author(s):  
Kadhim A. Aadim

Low-pressure capacitively coupled RF discharge Ar plasma has been studied using Langmuir probe. The electron temperature, electron density and Debay length were calculated under different pressures and electrode gap. In this work the RF Langmuir probe is designed using 4MHz filter as compensation circuit and I-V probe characteristic have been investigated. The pressure varied from 0.07 mbar to 0.1 mbar while electrode gap varied from 2-5 cm. The plasma was generated using power supply at 4MHz frequency with power 300 W. The flowmeter is used to control Argon gas flow in the range of 600 standard cubic centimeters per minute (sccm). The electron temperature drops slowly with pressure and it's gradually decreased when expanding the electrode gap. As the gas pressure increases, the plasma density rises slightly at low gas pressure while it drops little at higher gas pressure. The electron density decreases rapidly with expand distances between electrodes.


2013 ◽  
Vol 781-784 ◽  
pp. 55-58 ◽  
Author(s):  
Hong Jie Zhao ◽  
Zhen Hu ◽  
Zhan Guo Li

The Dielectric Barrier Discharge plasma (DBD) plasma was used to treat Diisopropyl fluorophosphate (DFP, a stimulant of sarin) in the air. The influence factors of degradation efficiency, including power, carrier gas flow velocity and initial concentration of DFP were investigated. As a result, the degradation efficiency increased with the power increasing. The degradation efficiency increased fastly when the power less than 105W, but slowly when the power more than 105W. The degradation efficiency decreased obviously with the carrier gas flow velocity increasing, because the time of DFP stayed in plasma reactor decreased and the concentration of DFP increased. The degradation efficiency rose firstly and then fell with the initial DFP increasing, when the initial concentration was less than 80 mg/m3, but decreased with the the initial concentration increasing, when the initial concentration was more than 80 mg/m3. The main products were acetone, isopropanol, phosphoric acid, pyrophosphoric acid, carbon dioxide and water, analyzed by GC-MS. Reaction mechanism was discussed according to degradation products.


Optik ◽  
2018 ◽  
Vol 155 ◽  
pp. 97-104
Author(s):  
Yangbao Deng ◽  
Shuguang Deng ◽  
Chao Tan ◽  
Cuixiu Xiong ◽  
Guangfu Zhang ◽  
...  

Author(s):  
David R. Huitink ◽  
Debjyoti Banerjee ◽  
Saion K. Sinha

This work demonstrates precise control over the synthesis conditions and location during CNT formation, such that single chirality tubes are obtainable. This technique obviates two significant hurdles that prevent the exploitation of CNTs in micro- and nano-devices. Microelectronic applications require precise location and chirality of synthesized CNTs. Conventional CVD synthesis techniques typically yield mixtures of CNTs (semi-conducting and metallic types) that grow at random locations. Dip Pen Nanolithography (DPN) techniques were used to deposit the catalysts at precisely defined locations and to pattern the catalysts on a substrate with specific sizes as well as to control the catalyst composition. After deposition of catalysts, a low temperature Chemical Vapor Deposition (CVD) process was used to synthesize CNT. Various known catalysts were deposited. Characterization studies before and after CVD synthesis of CNT showed that the CNT were of a single chirality as well as uniform diameter (with a very narrow range of variability). The results indicate that the chirality of the synthesized CNT can be controlled by changing the synthesis conditions (e.g., size of the catalyst patterns, composition of the catalysts, temperature of CVD, gas flow rates, etc.).


Chemosphere ◽  
2020 ◽  
Vol 258 ◽  
pp. 127334 ◽  
Author(s):  
Yunxia Ruan ◽  
He Guo ◽  
Jie Li ◽  
Zhengyan Liu ◽  
Nan Jiang ◽  
...  

Author(s):  
Yan Wu ◽  
Jie Li ◽  
Guo-Feng Li ◽  
Nan Li ◽  
Guang-Zhou Qu ◽  
...  

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