Studies On Measurement Of Gas Temperature Of Radio Frequency Atmospheric Pressure Discharge By OH Radical Emission Spectroscopy

RF atmospheric pressure discharge is widely used in material surface treatment,thin filmdeposition,sterilization,bio-medical due to advantages of low operation cost,low breakdown voltage,and the high active particle density.Because electrons frequently collision with neutral particles in the atmospheric pressure discharge,the problem of temperature rising is very serious.The gas temperature affects the discharge characteristics such as breakdown voltage,particle density and discharge mode transition.Gas temperature is an important parameter in industrial application.The gas temperature should be controlled within a certain range when dealing with the heat sensitive material and the active biological tissue.At present,there are many kinds of techniques to measure the gas temperature,which can be divided into two types: invasive and non-invasive.The emission spectrum of excited state is usually used to measure gas temperature of the radio frequency atmospheric pressure discharge.This method has the advantage of non-invasive,simple and high sensitivity.Although many studies about RF APGD have shown that with the increase of discharge power,the discharge mode is changed from alpha mode to gamma mode,and when the discharge mode is gamma mode,the gas temperature remains unchanged,but the results have problems.Therefore,the following works are done in this paper:?.Studies on the influence of instability of discharge system and measurement system on gas temperature.When discharge breakdown,the effect of temperature rising exists in the discharge system,and it is necessary to measure the spectral data after it reaches the heat balance.After the discharge system is stable,the influence of ICCD instability and light exposure on the background noise is studied.The results show that when the detector in the ICCD is cooled to-25 ?,the system does not achieve thermal equilibrium,and it will take about 70 minutes to reach the thermal equilibrium.When the ICCD reaches the heat balance,the light exposure also has an influence on the background noise.The influence of light exposure on background noise is mainly caused by dark current.The initial measurement needs about fifteen exposures,which effectively reduces the influence of exposure on background noise.?.Studies on the measurement of gas temperature by OH radical emission spectroscopy in RF atmospheric pressure discharge.With the increase of discharge power,the peak position of emission spectrum of OH radical in the atmospheric pressure discharge of the radio frequency is monotonic blue shift.Further analysis shows that the shift is not caused by the instrument error,but the collision shift.We measure gas temperature by the method of comparison of theoretical spectrum and experimental spectrum.In this experiment,the LIFBASE fitting software is used to calculate the gas temperature.When not consider the collision shift,we use two ways to calculate the gas temperature: wavelength correction only in minimum power and wavelength correction in each power.The results of the two ways are abnormal: as the discharge power increases,the gas temperature decreases.And the discharge mode transition from alpha to gamma model,the gas temperature remains unchanged as the discharge power increases.When we consider the collision shift,the abnormal phenomenon disappeared and the Chi-square error value corresponding to the gas temperature is small.After the discharge mode transition from alpha model to gamma model,with the discharge power increasing,the gas temperature rising is more serious.The comparison of the two results shows that the collision frequency shift must be taken into account when measuring the gas temperature with OH radical emission spectrum in the radio frequency atmospheric pressure discharge.The spectral line broadening of Ar emission spectrum verifies the physical law of the gas temperature and discharge power after the discharge mode turned gamma discharge mode.The results show that after the discharge mode turned gamma discharge mode,the Ar spectrum is still broadened,and the gas temperature is verified to increase.?.Studies on the influence of the intake means of gas on the gas temperature and volt ampere characteristic curve.The voltage waveform,current waveform and OH radical emission spectra of RF APGD were measured in different different ways(the air inlet is parallel the electrode plate and the air inlet is perpendicular to the electrode plate).And we calculated gap voltage,conduction current and gas temperature.The results show that when the air inlet is perpendicular to the electrode plate,the gas temperature is higher,and the discharge is more easily transformed into the gamma discharge mode.When the gas blows toward the electrode plate,the gas temperature decreases.