Characterization of a kHz sinusoidal Argon plasma jet impinging on water using Thomson scattering and fast imaging

Abstract

The electron dynamics in a stable and non-filamentary Argon plasma jet, generated using AC excitation at kHz frequencies and interacting with a liquid surface either at floating potential or electrically grounded were examined using laser Thomson scattering. In the case of a floating liquid, two discharge events were observed during each half-cycle of the applied sinusoidal voltage. In the grounded liquid case only one discharge event was observed, which occurred during the positive half period. Through spatio-temporal imaging of the discharge, its repetitive breakdown behavior was analyzed and divided into pre-, main-, and post-breakdown phases. The dynamics and presence of the various phases differed depending upon the grounding of the liquid. Thomson scattering measurements revealed maximum electron densities and temperatures of 6.0–6.3 × 1014 cm−3 and 3.1–3.3 eV for the floating liquid case and 1.1 × 1015 cm−3 and 4.3 eV in the grounded liquid case. Electron-driven reactions are the primary source of reactive chemical species in a plasma jet. Therefore, the electrical characteristics of the liquid sample can impact the fundamental physicochemical processes at play in the discharge, ultimately influencing its chemical composition.

Towards plasma jet controlled charging of a dielectric target at grounded, biased, and floating potential

“…The influence of the grounding conditions of a target under plasma exposure has been examined before regarding the electronic properties of the discharge. For a different coaxial-plasma jet operated using argon gas instead of helium and 5 s pulses (16 kHz), it was shown that the resistance of a conductive liquid target towards the ground determines whether it behaves as a DBD-type discharge (for a high impedance path to ground) or a DC-type (low impedance path to ground) 20 , 28 . This had significant consequences for the temporal dynamics of electron density and temperature in the center of the plasma plume.…”

Discharge aspects of a snake‐like plasma plume generated by an atmospheric pressure plasma jet with variable argon flow rate

“…Here, the recombination coefficient ( β ) equals to 10 −7 cm 3 /s for argon discharge, [ 39 ] and $${<mpadded xmlns="http://www.w3.org/1998/Math/MathML">n</mpadded>}_{e}^{0}$$ is in the range 10 13 −10 15 cm −3 for streamers. [ 82–84 ] Resultantly, τ r is 1.0 μs at most, which is several orders of magnitude shorter than a voltage cycle ( T = 0.5 ms). Therefore, residual electrons can be neglected.…”

Remote surface charge detection device for water with excess charge

“…Since, the charge due to the ions in the water are non-relativistic, the scattering of EM waves can probe charge analogous to the Thomson scattering, Rayleigh Scattering phenomenon etc The Thomson scattering has been explored in the plasma interaction with liquid surface in floating potential and grounded. The electron dynamics from the plasma to the liquid is studied with the Thomson scattering [31]. The non-equilibrium plasma at atmospheric pressure in contact with the liquid to study the vaporized water in contact [32].…”