Estimation of excitation temperature by duty ratio of observed period in non-equilibrium plasma

Abstract

We investigated the excitation temperature of atmospheric-pressure non-equilibrium (cold) plasma using a line-pair method. An atmospheric cold plasma was intermittently generated using a quartz tube, a rare gas, and a foil electrode by applying high-voltage alternating current. Because the plasma occurred intermittently, an interval appeared between each generated plasma bullet. We assessed the time-averaged effective intensity from the observed intensity at each wavelength measured using a spectrometer. When the exposure time of the spectrometer is longer than the observed period of the plasma emission light, the time-averaged effective intensity at each wavelength decreases because it includes the interval with no plasma emission light. The difference in intensity between wavelengths changes with frequency, because changing the frequency changes the interval between plasma bullets. Consequently, even if the plasma electron temperature does not depend on the frequency of the applied voltage, the excitation temperature estimated from the difference in intensity changes with the frequency. The plasma electron temperature can be estimated from the duty ratio of the observed period of plasma emission light, and we estimated the electron temperature in the helium and argon cold plasmas to be 1.0 eV.

Plasma activated medium prepared by a bipolar microsecond-pulsed atmospheric pressure plasma jet array induces mitochondria-mediated apoptosis in human cervical cancer cells

“…The characteristic spectral lines of helium were chosen to determine the excitation temperature ( T exc ) under a Boltzmann approximation [ 28 , 29 ]. Fig 3(C) presents the excitation temperature of the jet array as a function of the pulse width.…”

Determination of Helium-Discharge Atmospheric-Pressure Plasma Parameters and Distribution Using Numerical Simulation

“…The behavior of APPJs is important for understanding thermodynamic properties including gas temperature (T g ), rotational temperature (T rot ), excitation temperature (T exc ) and electron temperature (T e ) in the plasma [16][17][18][19]. Optical emission spectroscopy (OES) is a widely used technique to investigate such properties using experimental observations [20][21][22][23].…”

“…The excitation temperature (T exc ) describes the population of atomic excited states assuming that this follows a Boltzmann distribution. Considering the degeneracy of each atomic state, the population come by [18,19,41], and the CR model was applied to estimate the relations between the thermodynamic properties of AP-PJs. The distribution of chemical species along the direction of plasma jet propagation was estimated numerically using the GM.…”

Excitation Wavelength and Temperature at Irradiation of Metal by Atmospheric-Pressure Nonequilibrium Argon Plasma

“…[20][21][22][23] Plasma parameters (density and temperature) change with operation conditions, but with typical parameters, atmospheric-pressure nonequilibrium (cold) plasma can have a wide-ranging density of 10 17 -10 20 m -3 , and its temperature can be a few electron volts. 5,6,19,[24][25][26] Plasma intermittently generated by AC power supply is in a nonthermal equilibrium state. One study reported such plasma's electron temperature to be ~1 eV, 26 but ion and gas temperatures were close to room temperature.…”

“…5,6,19,[24][25][26] Plasma intermittently generated by AC power supply is in a nonthermal equilibrium state. One study reported such plasma's electron temperature to be ~1 eV, 26 but ion and gas temperatures were close to room temperature. 11 Therefore, it is thought that thermal damage to an object does not occur with plasma irradiation.…”