An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid b...An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid barrier-jet was shown to generate uniform discharge with a lower breakdown voltage and a relatively low gas temperature varying from 390 K to 440 K, even when the vol.% oxygen in argon was up to 6%. Utilizing the actinometry method, the concentration of atomic oxygen was estimated to be about in an orders of magnitude of 10^17 cm^-3. The argon/oxygen plasma jet was then employed to clean out heat transfer oil, with a maximum cleaning rate of 0.1 mm/s achieved.展开更多
Two experimental techniques have been used to quantify the atomic oxygen density in the case of hot air plasma generated by a microwave （MW） resonant cavity. The latter operates at a frequency of 2.45 GHz inside a c...Two experimental techniques have been used to quantify the atomic oxygen density in the case of hot air plasma generated by a microwave （MW） resonant cavity. The latter operates at a frequency of 2.45 GHz inside a cell of gas conditioning at a pressure of 600 mbar, an injected air flow of 12 L/min and an input MW power of 1 kW. The first technique is based on the standard two photon absorption laser induced fluorescence （TALIF） using xenon for calibration but applied for the first time in the present post discharge hot air plasma column having a temperature of about 4500 K near the axis of the nozzle. The second diagnostic technique is an actinometry method based on optical emission spectroscopy （OES）. In this case, we compared the spectra intensities of a specific atomic oxygen line （844 nm） and the closest wavelength xenon line （823 nm）. The two lines need to be collected under absolutely the same spectroscopic parameters. The xenon emission is due to the addition of a small proportion of xenon （1% Xe） of this chemically inert gas inside the air while a further small quantity of H2 （2~） is also added in the mixture in order to collect OH（A- X） and NH（A-X） spectra without noise. The latter molecular spectra are required to estimate gas and excitation temperatures. Optical emission spectroscopy measurements, at for instance the position z=12 mm on the axis plasma column that leads to a gas measured temperature equal to 3500 K, an excitation temperature of about 9500 K and an atomic oxygen density 2.09× 1017＋ 0.2×1017 cm-3. This is in very good agreement with the TALIF measurement, which is equal to 2.0×101T cm-3.展开更多
Optical emission spectroscopy measurements of dual-frequency capacitively coupled CF4 plasmas were carried out. The gas temperature （Tg） was acquired by fitting the optical emission spectra of a CF B-X system in 201...Optical emission spectroscopy measurements of dual-frequency capacitively coupled CF4 plasmas were carried out. The gas temperature （Tg） was acquired by fitting the optical emission spectra of a CF B-X system in 201～206 nm. The atomic fluorine concentration and the electron temperature （Te） were obtained by trace rare gas optical emission spectroscopy and a modified Boltzmann plot technique, respectively. It was found that the gas temperature was about 620±30 K at 50 mTorr and the atomic fluorine concentration increased while the electron temperature decreased with increasing gas pressure and power of high frequency （60 MHz）. With increasing low frequency （2 MHz） power, the electron temperature also increased, but the atomic fluorine concentration was insensitive to this change. The generation and disappearance mecha- nisms of F atoms are discussed.展开更多
基金supported by National Natural Science Foundation of China (Nos.10775026, 50537020, 50528707)
文摘An atmospheric pressure nonequilibrium argon/oxygen plasma jet assisted by the preionization of syringe needle electrode discharge is reported. With the syringe needle plasma as its pre-ionization source, the hybrid barrier-jet was shown to generate uniform discharge with a lower breakdown voltage and a relatively low gas temperature varying from 390 K to 440 K, even when the vol.% oxygen in argon was up to 6%. Utilizing the actinometry method, the concentration of atomic oxygen was estimated to be about in an orders of magnitude of 10^17 cm^-3. The argon/oxygen plasma jet was then employed to clean out heat transfer oil, with a maximum cleaning rate of 0.1 mm/s achieved.
文摘Two experimental techniques have been used to quantify the atomic oxygen density in the case of hot air plasma generated by a microwave （MW） resonant cavity. The latter operates at a frequency of 2.45 GHz inside a cell of gas conditioning at a pressure of 600 mbar, an injected air flow of 12 L/min and an input MW power of 1 kW. The first technique is based on the standard two photon absorption laser induced fluorescence （TALIF） using xenon for calibration but applied for the first time in the present post discharge hot air plasma column having a temperature of about 4500 K near the axis of the nozzle. The second diagnostic technique is an actinometry method based on optical emission spectroscopy （OES）. In this case, we compared the spectra intensities of a specific atomic oxygen line （844 nm） and the closest wavelength xenon line （823 nm）. The two lines need to be collected under absolutely the same spectroscopic parameters. The xenon emission is due to the addition of a small proportion of xenon （1% Xe） of this chemically inert gas inside the air while a further small quantity of H2 （2~） is also added in the mixture in order to collect OH（A- X） and NH（A-X） spectra without noise. The latter molecular spectra are required to estimate gas and excitation temperatures. Optical emission spectroscopy measurements, at for instance the position z=12 mm on the axis plasma column that leads to a gas measured temperature equal to 3500 K, an excitation temperature of about 9500 K and an atomic oxygen density 2.09× 1017＋ 0.2×1017 cm-3. This is in very good agreement with the TALIF measurement, which is equal to 2.0×101T cm-3.
基金supported by National Natural Science Foundation of China(No.10975029)the Important National Science and Technology Specific Project of China(No.2011ZX02403-001)
文摘Optical emission spectroscopy measurements of dual-frequency capacitively coupled CF4 plasmas were carried out. The gas temperature （Tg） was acquired by fitting the optical emission spectra of a CF B-X system in 201～206 nm. The atomic fluorine concentration and the electron temperature （Te） were obtained by trace rare gas optical emission spectroscopy and a modified Boltzmann plot technique, respectively. It was found that the gas temperature was about 620±30 K at 50 mTorr and the atomic fluorine concentration increased while the electron temperature decreased with increasing gas pressure and power of high frequency （60 MHz）. With increasing low frequency （2 MHz） power, the electron temperature also increased, but the atomic fluorine concentration was insensitive to this change. The generation and disappearance mecha- nisms of F atoms are discussed.
