ABSTRACT
Four styles of spectral line shape function and their transformation relation were investigated theoretically. The photon number and energy distribution as functions of frequency and wavelength resulting from Doppler broadening were investigated, and the maximum intensity and FWHM (full width at half maximum intensity) were obtained. The results show that the photon number distribution as function of frequency is almost the same as the energy distribution as function of frequency, while the photon number distribution as function of wavelength is almost the same as the energy distribution as function of wavelength. The method has been presented by analyzing the Doppler spectral line shape function, with which the ratio of density between two spectral lines can be obtained according to the ratio of maximum value of two spectral lines.
ABSTRACT
Dielectric barrier discharge has become a hot issue in low temperature plasma research field because of wide prospect for its application in industry. In the present paper, an uniform glow discharge was realized in atmospheric pressure helium with a parallel planar dielectric barrier discharge device and an uniform plasma was generated in helium at atmospheric pressure. Electrical method was used to separate the discharge current from the total current signal and the waveform of discharge current could be obtained. The relations among the discharge current, applied voltage, gap voltage and wall charge during the uniform glow discharge were used to analyze the dynamical behavior of wall charges during their accumulation. The results show that the wall charges were mainly accumulated during the existence of discharge current pulse, while the quantity of wall charges continued to increase until the gap voltage changed its polarity after the disappearance of discharge current pulse, and finally the quantity of wall charges decreased until the next breakdown. These experimental results are important for the further study of wall charges' effect in the dielectric barrier glow discharge and its application in industry.
ABSTRACT
The electron excitation temperature was measured by the intensity ratio of two spectral lines in argon dielectric barrier discharge (DBD) at atmospheric pressure. The spectral range is from 690 to 800 nm. It is shown that all of the spectral lines are attributed to neutral Ar atoms. The spectral line 763.51 nm (2P(6)-->1S(5)) and 772.42 nm (2P(2)-->1S(3)) are chosen to estimate the electron excitation temperature. The experimental results show that the electron excitation temperature is in the range of 0.1-0.5 eV. The electron excitation temperature increases with increasing applied voltage, but decreases with increasing gas flow rate. The electron excitation temperature in flowing Ar gas discharge is much different from that in static Ar gas discharge. The result is of great importance to industrial application of DBD.
Subject(s)
Argon/chemistry , Atmospheric Pressure , Electrons , Temperature , Algorithms , Electrochemical Techniques/instrumentation , Electrochemical Techniques/methods , Spectrophotometry/methodsABSTRACT
The global light emission of dielectric barrier discharge with pattern mode in air was measured and compared with the global current obtained with a small resistor. The results show that the moments and the amplitudes of the pulses in light emission correspond to those in the global current, respectively. So the discharge current can be measured by optical methods. Further more, the temporal aspect of the microdischarges in dielectric barrier discharge was obtained by using this method. It is believed that the results are of great importance to the study of spatiotemporal dynamics in dielectric barrier discharge, and are valuable to the study of gas discharge as well.
ABSTRACT
The experimental setup of dielectric barrier discharge was designed which is propitious to optical measurement. Temporal behavior of light emission of dielectric barrier discharges (filamentary model) in air at atmospheric pressure was measured by using optical method. Temporal behavior of dielectric barrier discharges was obtained. The experimental results show that the discharge burst in each half cycle of applied voltage consists of a series of discharge pulses, the duration of each discharge pulse is about 30-50 ns, and the interval of the neighboring discharge pulses is about a few hundred ns. The result is of great importance to the application of dielectric barrier discharges.
