التحقق من خصائص بلازما الهيليوم النفاث عند الضغط الجوي

Investigation on Characterization of Helium Atmospheric Pressure Plasma Jet

ABSTRACT

Characteristics of atmospheric pressure helium plasma jet (APHPJs) is significant because of their use in different application such as medical, biomedical, agriculture, and industry. In this work, a developed dielectric barrier discharge (DBD) system was used to study the properties of (APHPJs) in the advanced plasma laboratory at the University of Kerbala, College of Science, Department of Physics. The device components are a high voltage (0-20)kV alternating current generator, Pyrex tubes of different thicknesses (0.1, 0.2, 0.5, 1) mm, two electrodes which are made of aluminum with a thickness of 1 mm placed around the Pyrex, and the working gas for electrical discharge is helium (He). Plasma temperature and plasma plume length play a major role in various cold plasma applications, therefore the effects of tube thickness and distance between the electrodes on electrical characteristics (plume length and plasma temperature) of generated plasma are investigated. A simple electronic thermo-sensor of the type (UTS) is used to estimate the temperature of the plasma and the plasma plume measured by standard metric. The plasma temperature and the length of the flame are estimated for different gas flow rates (1-6) L/min and a range of applied voltage (8-14) kV.
The optical emission spectroscopy (OES) method is used to record and analyze the spectrum of helium plasma jet for a range of applied voltage (8-14) kV and flow rate of helium gas (1-6) L/min. Electron temperature (Te) and electron density (ne) are calculated using the Boltzmann plot method and considered in the database recorded in the NIST.
The results show that the plasma plume length is random variation due to the thickness of the Pyrex tube, then the optimization characteristic is obtained when the applied voltage is 8kV and the gas flow rate is (4L/min) in the case of 1mm thickness of Pyrex tube, the length of the plasma plume is 6cm and the plasma temperature is confined between (24-26) ºC, which is close to room temperature. When the distance between the electrodes is at a range (1-2.5) cm, the applied voltage is (8 kV) and the helium flow rate is 4L/min, the plasma is generated but its plume length decreases as the distance increases, as well as the plasma temperature, has the same behavior.
Spectra of Helium plasma jets at atmospheric pressure for voltage (1-14) kV and a rate of flow (1-6) L/min are recorded and analyzed, and the spectrum lines in the helium plasma jet appear in the UV-Vis-NIR regions. Six spectral lines of the reactive species radicals of the generated plasma were used to estimate the (Te) and (ne). The optimum working parameters to generate helium plasma with good properties are the rate of gas flow is 4L/min and the employed voltage of 8 kV. The optimum characteristic of generated plasma in this work is a plume length of 6 cm, plasma temperature is 26ºC, and high reactive species intensity of (O2,N2,OH,NO) are (357,875, 2476,403) respectively, and the temperature of the electron is less than 1eV(6102.22K), and the electron density is (1.57×1013 cm-3). The generated (APHPJs) can be used in biomedical and medical applications due to the high intensity of reactive species, Also the values of electron temperature (Te) and electron density (ne) are in the range of artificial plasma.