Investigation on the electron density and temperature in a nanosecond pulsed helium plasma jet with Thomson scattering

Wu, Fan; Li, Jiayin; Xian, Yuezhong; Tan, Xiao; Lü, Xinpei

doi:10.1002/ppap.202100033

“…According to the ndings, the density and temperature of electrons increased proportionally with the increase in laser energy (500-800) mJ. Due to the signi cant e ect of the increase (Wu et al, 2021) . By exposing the plasma to laser light for a longer duration, more ablation is produced, which increases the number of excited atoms and, consequently, the peak intensity values of the spectral lines of the plasma emission, as depicted in the pervious gure.…”

Section: Resultsmentioning

confidence: 96%

“…Debye shielding 𝜆 D is a charged particle response that reduces the impact of electricity on local elds, giving the plasma its quasi-neutrality. To refer to the length of Debye 𝜆 D , we can use the abbreviation 𝜆 D and calculate from Equation (4) (Wu et al, 2021) :…”

Section: Resultsmentioning

confidence: 99%

Study the Impact of Laser Energy on Laser-Induced Copper Plasma Parameters By Spectroscopic Analysis Technique

Abbas

¹

2022

Sci. Technol. Indones

3

0

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In this paper, spectroscopic analysis (OES) for copper (Cu) plasma was achieved at atmospheric pressure. Q switched Nd: YAG pulsed laser with a fundamental wavelength (1064 nm), energy range (500-800) mJ, frequency (6 Hz), and laser pulses (10-30 pulses) was applied to induce copper plasma. Based on the spectroscopic analysis, plasma parameters like electron temperature (Te), electron density (ne), Debye length (λD), and plasma frequency (fp) have been calculated. The results demonstrated that the laser energy affects all plasma parameters, with an electron temperature (Te) range of (0.6820-0.8949) eV and electron number density (ne) range of (13.667-17.235)×1017 cm−3. Also, the image of the place of laser bombardment of copper (Cu) metal shows three diameters or circles, each circle bears a different color from the other. It can be described as a crater, and the interaction of the laser with copper metal is obvious by laser ablation, and here the effect of the increased energy of the laser appears during the spectroscopic diagnosis and the process of metal bombardment.

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“…The pore size was within the range of the Debye length of the He plasma. A higher applied voltage induced a smaller Debye [2,17,38]. When the voltage was too low, the Debye length was larger than the pore size in the kaolin layer and plasma species could not penetrate in the pore, e.g.…”

Section: Influence Of the Parameter On Plasma Penetrationmentioning

confidence: 99%

Penetration of plasma jet into porous dielectric layer: confirmed by surface charge dissipation of silicone rubber

Li¹,

Fu²,

Guo³

et al. 2022

J. Phys. D: Appl. Phys.

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The penetration of plasma in the porous structure is important for its application in plasma catalysis, plasma medicine, etc. In this paper, the penetration of plasma species in the porous kaolin layer was investigated. The silicone rubber was chosen as a probe and the inorganic porous dielectric layer was constructed with granular kaolin coated on the surface of silicone rubber. AC and pulsed plasma jets were applied to the silicone rubber, and the surface charge dissipation of bulk silicone rubber was measured to characterize the changes of surface property caused by the plasma penetration. The results showed that plasma could penetrate the porous dielectric layer on the silicone rubber and interact with the surface of silicone rubber, thus accelerating the surface charge dissipation of the bulk silicone rubber. The increase of shallow traps and surface conductivity after plasma treatment was the main reason for the acceleration of surface charge dissipation. The surface charge dissipation is enhanced with the increase of treatment time and the generating voltage of plasma. The surface charge dissipation declined for silicone rubber with a thicker kaolin layer due to the blocking of the kaolin layer on the interaction of plasma and the silicone rubber. For the same kind of plasma, the charge dissipation rate was linearly related to plasma dose which was represented by the energy density of plasma applied on the coated silicone rubber. At the same energy density, the surface charge dissipation of silicone rubber after pulsed plasma treatment was faster than that of AC plasma.

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“…During two recent decades numerous studies devoted to the short (sub-µs) pulsed He-based plasma jets and their physical properties were published, dealing with several effects such as gas heating [46,48], electron temperature and density [37,[49][50][51], the role of gas admixtures [43,52], as well as the ionization waves, in particular their structure [29,53] and propagation dynamics [30,31]. Some works are focused on the applied (high-) voltage and electric field dynamics in the discharge [54,55], as these parameters are critical for understanding of the ns-discharge physics, such as gas breakdown, ionization wave propagation and related phenomena.…”

Section: Introductionmentioning

confidence: 99%

Diagnostics of a nanosecond atmospheric plasma jet. Electron and ro-vibrational excitation dynamics

Britun¹,

Christy²,

Gamaleev³

et al. 2022

Plasma Sources Sci. Technol.

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Atmospheric repetitive He discharge with 10 ns current peak width and 3 × 10 11 V s−1 voltage front rise working in jet geometry is studied. The first part of the study is devoted to electrical and optical discharge characterization including voltage-current behavior, emission dynamics, as well as ro-vibrational dynamics of N2, N 2 + and OH molecules. It is found that He atoms get excited at the very early stage, as a result of ionization wave formation. This process follows by excitation of O, N2 and N 2 + . It is also shown that a rather small (0.1%–1%) air admixtures facilitate gas breakdown, as revealed by shortening of the discharge current risetime. The rotational excitation of N 2 + always overtakes He excitation by about 5 ns, with rotational temperature peaking at about 650 K and decaying afterwards, whereas rotational temperature of N2 always remains constant equal to about 300 K. This value is associated with gas kinetic temperature since the electron-rotational (e-R) excitation process is too slow, so it cannot be activated during the plasma phase and no additional change in rotational excitation of N2 happens. Nitrogen molecules remain vibrationally excited in the discharge, post-discharge and jet areas after the plasma pulse which is likely a result of ionization wave propagation. Upon water vapor injection the apparent OH rotational distributions reveal double Boltzmann slope representing thermalized and non-thermalized OH groups. Rotational temperature of the thermalized group correlates with the one of N 2 + showing, however, much longer relaxation time, whereas for the non-thermalized group it remains above 1 eV at all conditions. The obtained results confirm that the studied ns- discharge is a good candidate for temperature-sensitive applications, such as the bio-sample treatment. Further analysis related to the ionization waves, electron density and electric field behavior is undertaken in the second part.

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Investigation on the electron density and temperature in a nanosecond pulsed helium plasma jet with Thomson scattering

Cited by 19 publications

References 35 publications

Study the Impact of Laser Energy on Laser-Induced Copper Plasma Parameters By Spectroscopic Analysis Technique

Study the Impact of Laser Energy on Laser-Induced Copper Plasma Parameters By Spectroscopic Analysis Technique

Penetration of plasma jet into porous dielectric layer: confirmed by surface charge dissipation of silicone rubber

Diagnostics of a nanosecond atmospheric plasma jet. Electron and ro-vibrational excitation dynamics

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