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Investigation on the electron density and temperature in a nanosecond pulsed helium plasma jet with Thomson scattering
Author(s) -
Wu Fan,
Li JiaYin,
Xian YuBin,
Tan Xiao,
Lu XinPei
Publication year - 2021
Publication title -
plasma processes and polymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 74
eISSN - 1612-8869
pISSN - 1612-8850
DOI - 10.1002/ppap.202100033
Subject(s) - thomson scattering , electron density , atomic physics , scattering , rayleigh scattering , electron temperature , electron , nanosecond , plasma , jet (fluid) , materials science , optics , physics , laser , nuclear physics , thermodynamics
Diagnostic of spatiotemporal distribution of the electron density and temperature of atmospheric pressure plasma jets is a difficult task, as Thomson scattering, which is the most used measurement, suffers from the stray light induced by Rayleigh scattering. In this paper, a new strategy is reported to restrain the stray light in Thomson scattering. With a physical mask placed at the output of a single spectrometer, the scattering signal is obtained with a relatively high ratio of signal to noise. The electron density in a pulsed kHz‐driven atmospheric plasma jet interacting with a dielectric target is measured by using this method. A donut‐shaped distribution of electron density is observed at an axial position 1 mm away from the nozzle. The radius of the ring structure decreases with the reduction of the gas flow rate. The electron density reaches a maximum of about 4.5 × 10 20 m −3 at a delay time of 150 ns from the onset of the pulse. A similar time relationship between the electron density and plasma emission intensity is also identified. Higher applied voltage leads to a faster increasing and a higher peak value of the electron density. Pulse width shows little impact on the generation and decay of electrons.