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1.
Junxia RAN 《等离子体科学和技术》2020,22(10):105401
Fast photography and optical emission spectroscopy are implemented in a 5 mm neon gap dielectric barrier discharge (DBD) at atmospheric pressure with quartz glass used as the dielectric layer. Results show that it starts with a Townsend discharge and ends at a sub-normal glow discharge in neon DBD. Based on the Townsend discharge, the first ionization coefficient of neon is measured. The measurements are consistent with those at low pressure. Optical emission spectroscopy indicates that the spectra are mainly composed of atomic lines of neon, molecular bands and molecular ion bands originating from inevitable gas impurities (mainly nitrogen). Moreover, spectral lines emitted from atomic neon corresponding to the transitions (2p5 3p → 2p5 3s) are predominant. Although the second positive system of N2(C3Πu → B3Πg) is observed, their intensities are too weak compared with neon's spectrum. The molecular nitrogen ion line of 391.4 nm is observed. It reveals that Penning ionization between high energy neon excited states and the inevitable gas impurities plays an important role in the value of the α coefficient. 相似文献
2.
Yinxia GUAN 《等离子体科学和技术》2019,21(5):54007-65
This research mainly describes the generation and diagnosis of plasma using a wire-plate discharge device driven by different power supplies, aimed at investigating the effect of driving source parameters on micro-discharge induced by a corona. The influence of parameters such as waveform, duty ratio and bias voltage on discharge characteristics was explored preliminarily. Experiment results show that the determination of volt-ampere characteristics under different driving source waveforms indicates that the application of square and pulse waveforms shows great advantages over that of sawtooth and sinusoidal waveforms. Similarly, the photo-thermal effects of the system were investigated by comparing the high-voltage electrode temperature and relative emission intensity of N2 (C3Пu →B3Пg , 0–0, 337 nm), where square and pulse waveforms also achieved better performance. But the pulse waveform had a slight advantage over the square waveform in terms of energy conversion. Further, investigations of the duty ratio and bias voltage applied on the pulse waveform were conducted, and the results indicate that the duty ratio could effectively improve the discharge power and thermal effect to a certain extent; however, the application of bias voltage on the pulse signal had little influence on the discharge power and thermal effect. 相似文献
3.
Panagiotis SVARNAS 《等离子体科学和技术》2013,15(9):891-895
Optical emission spectroscopy parallel to the axis of a low-pressure radio-frequency discharge in nitrogen was realized,i.e.end-on instead of customary side-on measurements.A specially designed optical feedthrough was fabricated and installed co-planar with the anode electrode,allowing non-invasive observations perpendicular to the plasma sheath.The principal excited species flowing towards the grounded electrode were identified and,by assuming Boltzmann distributions,the vibrational temperature of the molecules on the X1∑+g and C3Πu levels was estimated under various operating conditions. 相似文献
4.
5.
In this study, dielectric barrier discharge plasma and ozone(O_3) were combined to synergistically degrade trans-ferulic acid(FA), and the effect of water quality on FA degradation was studied. The results showed that 96.9% of FA was degraded after 40 min treatment by the plasma/O_3 process. FA degradation efficiency increased with the p H values. The presence of suspended solid and humic acid inhibited FA degradation. FA degradation efficiency increased as the water temperature increased to 30 °C. However, the further increase in water temperature was adverse for FA degradation. Effects of common inorganic ions on FA degradation were also investigated. The addition of Cl~- inhibited the FA degradation, whileCO_3~(2-) had both negative and positive influences on FA degradation.NO_3~- andSO_4~(2-) did not have significant effect on FA degradation. Fe~(3+)and Cu~(2+)benefited FA degradation through the Fenton-like and catalytic ozonation reactions. 相似文献
6.
UV-pulsed laser cavity ringdown spectroscopy of the hydroxyl radical OH(A–X)(0–0)band in the wavelength range of 306–310 nm was employed to determine absolute number densities of OH in the atmospheric helium plasma jets generated by a 2.45 GHz microwave plasma source.The effect of the addition of molecular gases N_2 and O_2 to He plasma jets on OH generation was studied.Optical emission spectroscopy was simultaneously employed to monitor reactive plasma species.Stark broadening of the hydrogen Balmer emission line(H_β)was used to estimate the electron density nein the jets.For both He/N_2 and He/O_2 jets, newas estimated to be on the order of 10~(15)cm~(-3).The effects of plasma power and gas flow rate were also studied.With increase in N_2 and O_2 flow rates, netended to decrease.Gas temperature in the He/O_2 plasma jets was elevated compared to the temperatures in the pure He and He/N_2 plasma jets.The highest OH densities in the He/N_2 and He/O_2 plasma jets were determined to be 1.0?×10~(16)molecules/cm~3 at x?=?4 mm(from the jet orifice)and 1.8?×?10~(16)molecules/cm~3 at x=3 mm, respectively.Electron impact dissociation of water and water ion dissociative recombination were the dominant reaction pathways, respectively, for OH formation within the jet column and in the downstream and far downstream regions.The presence of strong emissions of the N_2~+ bands in both He/N_2 and He/O_2 plasma jets, as against the absence of the N_2~+ emissions in the Ar plasma jets, suggests that the Penning ionization process is a key reaction channel leading to the formation of N_2~+ in these He plasma jets. 相似文献
7.
《等离子体科学和技术》2021,23(9):95405
In this paper,unipolar pulse (including positive pulse and negative pulse) and bipolar pulse voltage are employed to generate diffuse gas–liquid discharge in atmospheric N_2with a rumpetshaped quartz tube.The current–voltage waveforms,optical emission spectra of excited state active species,FTIR spectra of exhaust gas components,plasma gas temperature,and aqueous H_2O_2,NO_2~-,andNO_3~-production are compared in three pulse modes,meanwhile,the effects of pulse peak voltage and gas flow rate on the production of reactive species are studied.The results show that two obvious discharges occur in each voltage pulse in unipolar pulse driven discharge,differently,in bipolar pulse driven discharge,only one main discharge appears in a single voltage pulse time.The intensities of active species (OH(A),and O(3p)) in all three pulsed discharge increase with the rise of pulse peak voltage and have the highest value at 200 ml min~(-1)of gas flow rate.The absorbance intensities of NO_2and N_2O increase with the increase of pulse peak voltage and decrease with the increase of gas flow rate.Under the same discharge conditions,the bipolar pulse driven discharge shows lower breakdown voltage,and higher intensities of excited species (N_2(C),OH(A),and O(3p)),nitrogen oxides (NO_2,NO,and N_2O),and higher production of aqueous H_2O_2,NO_2~-,andNO_3~-compared with both unipolar positive and negative discharges. 相似文献
8.
In this paper, the generation of excimers and exciplexe radiation in mixtures of rare gas with halogen by homogeneous dielectric barrier discharge (DBD) is investigated. The typical characteristics of an excilamp based on KrCl exciplexe molecules and the kinetic processes for the formation and the decay of this molecules in the Kr/Cl2 mixture are studied. The computer model developed is based on the Kr/Cl2 mixture chemistry, the equivalent electric circuit and the Boltzmann equations. The importance in the kinetic processes of some species such as the metastable state of Krypton (Kr(3P0,2)) and the negative ion of chloride (Cl) is considered. The results illustrate the time variations of charged species (ne,Kr+,Cl,Cl+,Cl+2,Kr+2), excited atoms and molecules (Kr(3P0,2), Kr(3P1), Cl, Cl2), the excimers (Kr2,KrCl(B),KrCl(C),Kr2Cl) and the UV photon concentrations (in 222nm,235nm,258nm and 325nm range). The effects of chlorine concentration and the total gas pressure in the Kr-Cl2 discharge on the electric parameters and radiation emissions are investigated. 相似文献
9.
Feng LIU 《等离子体科学和技术》2022,24(5):54004
Dielectric barrier discharges (DBDs) have been widely used in ozone synthesis, materials surface treatment, and plasma medicine for their advantages of uniform discharge and high plasma-chemical reactivity. To improve the reactivity of DBDs, in this work, the O2 is added into Ar nanosecond (ns) pulsed and AC DBDs. The uniformity and discharge characteristics of Ar ns pulsed and AC DBDs with different O2 contents are investigated with optical and electrical diagnosis methods. The DBD uniformity is quantitatively analyzed by gray value standard deviation method. The electrical parameters are extracted from voltage and current waveforms separation to characterize the discharge processes and calculate electron density ne. The optical emission spectroscopy is measured to show the plasma reactivity and calculate the trend of electron temperature Te with the ratio of two emission lines. It is found that the ns pulsed DBD has a much better uniformity than AC DBD for the fast rising and falling time. With the addition of O2, the uniformity of ns pulsed DBD gets worse for the space electric field distortion by O2−, which promotes the filamentary formation. While, in AC DBD, the added O2 can reduce the intensity of filaments, which enhances the discharge uniformity. The ns pulsed DBD has a much higher instantaneous power and energy efficiency than AC DBD. The ratio of Ar emission intensities indicates that the Te drops quickly with the addition of O2 both ns pulsed and AC DBDs and the ns pulsed DBD has an obvious higher Te and ne than AC DBD. The results are helpful for the realization of the reactive and uniform low temperature plasma sources. 相似文献
10.
《等离子体科学和技术》2016,18(9):918-923
Plasma source is the most important part of the laboratory plasma platform for fundamental plasma experimental research. Barium oxide coated cathode plasma source is well recognized as an effective technique due to its high electron emission current. An indirectly heated oxide coated cathode plasma source has been constructed on a linear magnetized plasma device. The electron emission current density can reach 2 A/cm 2 to 6 A/cm 2 in pulsed mode within pulse length 5–20 ms. A 10 cm diameter, 2 m long plasma column with density 10 18 m −3 to 10 19 m 3 and electron temperature Te ≈ 3–7 eV is produced. The spatial uniformity of the emission ability is less than 4% and the discharge reproducibility is better than 97%. With a wide range of the plasma parameters, this kind of plasma source provides great flexibility for many basic plasma investigations. The detail of construction and initial characterization of oxide coated cathode are described in this paper. 相似文献
11.
S. Y. Kim M. Harada H. Tomiyasu Y. Ikeda Y. Y. Park 《Progress in Nuclear Energy》2000,37(1-4):399-404
The structural and kinetic studies of U(VI) complex with benzamidoxime(Hba) as ligand in CD3COCD3 have been studied by means of 1H and 13C NMR. The Hba molecule was found to coordinate to UO22+ in the form of anionic benzamidoximate (ba), and the number of ba coordinated to UO22+ was determined to be 3 by analyzing the chemical shift of 13C NMR signal for Hba in the presence of UO22+. The exchange rate constants(kex) of ba in [UO2(ba)3] were determined by the NMR line-broadening method. The kinetic parameters were obtained as follows: kex(25°C) = 3.1 × 103s−1, ΔH≠ = 35.8 ± 3.5 KJ mol−1, and ΔS≠ = −65 ± 13.7 J K−1 mol−1. The UV-visible absorption spectra of solutions containing UO22+ and Hba were also measured. The molar extinction coefficient of the complex was found to be extremely large compared with those of UO2(L)52+ (L = unidentate oxygen donor ligands) complexes. This is due to the strong electron withdrawing of UO22+ from Hba and suggests that an interaction between UO22+ and Hba is very strong. Such a high affinity of monomeric amidoxime to UO22+ reasonably explains the high adsorptibility of amidoxime resin to U(VI) species, and is considered to result in the high recovery of U(VI) species from sea water using amidoxime resin. 相似文献
12.
Bing QI 《等离子体科学和技术》2019,21(8):85402-52
In this study, the density of metastable He2* in an atmospheric-pressure plasma jet operating in helium with 0.001% nitrogen has been measured using an auxiliary measuring electrode technique. In the glow discharge mode, waveforms from two grounding electrodes, including one main discharge electrode and one auxiliary electrode, are captured. The isolated current peak formed by Penning ionization in waveforms from the auxiliary measuring electrode is identified to calculate the density of metastable He2*. In our discharge environment, the helium metastable densities along the jet axis direction are between 2.26× 1013 and 1.74× 1013 cm-3, which is in good agreement with the results measured by other techniques. This measurement technique can be conveniently applied to the diagnosis of metastableHe2* in an atmospheric-pressure plasma jet array. 相似文献
13.
Kefeng SHANG 《等离子体科学和技术》2019,21(7):75502-140
A double-chamber gas-liquid phase DBD reactor (GLDR), consisting of a gas-phase discharge chamber and a gas-liquid discharge chamber in series, was designed to enhance the degradation of benzene and the emission of NOx. The performance of the GLDR on discharge characteristics, reactive species production and benzene degradation was compared to that of the single-chamber gas phase DBD reactor (GPDR). The effects of discharge gap, applied voltage, initial benzene concentration, gas flow rate and solution conductivity on the degradation and energy yield of benzene in the GLDR were investigated. The GLDR presents a higher discharge power, higher benzene degradation and higher energy yield than that of the GPDR. NO2 emission was remarkably inhibited in the GLDR, possibly due to the dissolution of NO2 in water. The benzene degradation efficiency increased with the applied voltage, but decreased with the initial concentration, gas flow rate, and gas discharge gap, while the solution conductivity presented less influence on benzene degradation. The benzene degradation efficiency and the energy yield reached 61.11% and 1.45 g kWh–1 at 4 mm total gas discharge gap, 15 kV applied voltage, 200 ppm benzene concentration, 0.2 L min−1 gas flow rate and 721 μS cm−1 water conductivity. The intermediates and byproducts during benzene degradation were detected by FT-IR, GC-MS and LC-MS primarily, and phenols, COx, and other aromatic substitutes, O3, NOx, etc, were determined as the main intermediates. According to these detected byproducts, a possible benzene degradation mechanism was proposed. 相似文献
14.
In this paper,volume coupled surface barrier discharge(V-SBD) with three structures possessing different volumes is excited by sine AC power in atmospheric air.Discharge images,waveforms of applied voltage and discharge current,and optical emission spectra simulating rotational and vibrational temperatures are recorded and analyzed.The effects of applied voltage on emission intensities of N_2(C~3Π_u→ B~3Π_g) and N_2~+(B~2∑_u~+ → X~2E_g~+),and rotational and vibrational temperatures are investigated.The results show that as applied voltage rises,emission intensities and rotational temperatures increase while vibrational temperatures decrease.In addition it is found that,as applied voltage varies,the rotational temperature of surface discharge changes faster than that of volume discharge. 相似文献
15.
A. SAEED A. W. KHAN M. SHAFIQ F. JAN M. ABRAR M. ZAKA-UL-ISLAM M. ZAKAULLAH 《等离子体科学和技术》2014,16(4):324-328
Optical emission spectroscopy is used to investigate the nitrogen-hydrogen with trace rare gas (4% Ar) plasma generated by 50 Hz pulsed DC discharges. The filling pressure varies from 1 mbar to 5 mbar and the current density ranges from 1 mA·cm −2 to 4 mA·cm −2 . The hydrogen concentration in the mixture plasma varies from 0% to 80%, with the objective of identifying the optimum pressure, current density and hydrogen concentration for active species ([N] and [N 2 ]) generation. It is observed that in an N 2 -H 2 gas mixture, the concentration of N atom density decreases with filling pressure and increases with current density, with other parameters of the discharge kept unchanged. The maximum concentrations of active species were found for 40% H 2 in the mixture at 3 mbar pressure and current density of 4 mA·cm −2 相似文献
16.
《等离子体科学和技术》2017,19(4):45501
This study aimed to discuss the removal of hydrogen sulfide(H_2S)with non-thermal plasma produced by a multilayer tubular dielectric barrier discharge reactor,which is useful in the field of plasma environmental applications.We explored the influence of various factors upon H_2S removal efficiency(η_(H_2S))and energy yield(Ey),such as specific energy density(SED),initial concentration,gas flow velocity and the reactor configuration.The study showed that we can achieveη_(H_2S)of 91%and the best Ey of 3100 mg kWh~(-1)when we set the SED,gas flow velocity,initial H_2S concentration and layers of quartz tubes at 33.2 J 1~(-1),8.0 m s~(-1),30 mg m~(-3)and five layers,correspondingly.The average rate constant for the decomposition of hydrogen sulfide was 0.206 gm~(-3)s~(-1).In addition,we also presented the optimized working conditions,byproduct analysis and decomposition mechanism. 相似文献
17.
Huijuan WANG 《等离子体科学和技术》2020,22(10):105504
In the paper, a hybrid gas–liquid dielectric barrier discharge (DBD) plasma system was set up to treat a methylene blue (MB) solution. The effects of the change of the carrier gas, the gas bubbling rate and different kinds of scavenger addition, including sodium carbonate (Na2CO3), para benzoquinone (p-BQ), triethylenediamine and sodium dihydrogen phosphate (NaH2PO4), on the MB decoloration were reviewed to clarify the critical active species for the dye decoloration in the DBD plasma system. The obtained results show that higher decoloration of the MB solution could be achieved when O2 was used as the carrier gas, which could be 100% after 20 min discharge treatment, and the result confirmed the crucial effect of O3 in the MB decoloration. Based on the experiments of the scavenger addition, it could be concluded that O2− and 1O2 were two other important reactive oxygen species (ROS) for the MB decoloration. The results of the higher chemical oxygen demand removal and faster disappearance of the characteristic peak of the MB from the UV–vis analysis under O2 bubbling conditions also proved the critical effect of the ROS formed by O2 on the MB decoloration. 相似文献
18.
铀在生物体内的化学形态及分布是评价铀毒性的基础。文章通过尾静脉注射给药方式研究螯合剂对染铀小鼠体内铀分布的影响。通过建立包含主要体液金属离子、小分子配体及UO22+与螯合剂的热力学平衡模型,采用数值模拟方法研究UO22+在血液中的形态。实验结果表明:DTPA易与UO22+形成[(UO2)2(OH)DTPA]2-,对小鼠血液中的UO22+有明显的促排作用,但在促排的同时对小鼠的肾脏和骨骼有损伤;抗坏血酸对小鼠体内各组织器官的铀促排几乎无作用,但形成的[(UO2)2(OH)Ascorbate]2+会阻碍肾脏中U(Ⅵ)的代谢;NTA对小鼠体内各组织器官铀的促排作用小,并会促使体内出现固相(UO2)3(PO4)2·4H2O,对骨骼有较强的损伤作用,不适合作为铀的促排剂。 相似文献
19.
Structural study on uranyl ion in 1-butyl-3-methylimidazolium nonafluorobutanesulfonate ionic liquid
The structure of uranyl ion in 1-butyl-3-methylimidazolium nonafluorobutanesulfonate ionic liquid (BMINfO) has been studied with 1H- and 35Cl-NMR, Raman, and UV-visible spectroscopy. In the 1H-NMR spectrum of the BMINfO solution prepared by dissolving UO2(ClO4)2·5 6H2O, the signal of H2O coordinated to UO22+ was observed at 6.64 ppm at 50°C (free H2O in BMINfO: 3.1 ppm at 50°C), suggesting that the uranyl species exists as the aquo complex, [UO2(H2O)n]2+. The signal of the coordinated H2O disappears with heating at 120°C for 3 h under vacuum. This indicates the dehydration from [UO2(H2O)n]2+. On the other hand, the 35Cl-NMR signal of ClO4− as the counter anion of UO22+ was observed at 1011 ppm (vs. Cl− in D2O) regardless of heating. This indicates that no ClO4− ion is in the first coordination sphere of UO22+. Furthermore, the UV-visible absorption spectra showed that the characteristic absorption bands due to UO22+ were sharpened with the dehydration. This means the simplification of the structure around UO22+. These results described above suggest that UO22+ in BMINfO has no ligand in its equatorial plane after the dehydration, i.e. UO22+ exists as a bare cation in this system. 相似文献
20.
Yen Theng LAU 《等离子体科学和技术》2022,24(11):114001
The characteristics of a low power 50 Hz argon plasma for surface treatment of polytetrafluoroethylene (PTFE) film is presented in this article. The current–voltage behavior of the discharge and time-varying intensity of the discharge showed that a DC glow discharge was generated in reversed polarity at every half-cycle. At discharge power between 0.5 and 1 W, the measured electron temperature and density were 2–3 eV and ∼108 cm−3, respectively. The optical emission spectrum of the argon plasma showed presence of some 'impurity species' such as OH, N2 and H, which presumably originated from the residual air in the discharge chamber. On exposure of PTFE films to the argon glow plasma at pressure 120 Pa and discharge power 0.5 to 1 W, the water contact angle reduced by 4% to 20% from the original 114° at pristine condition, which confirms improvement of its surface wettability. The increase in wettability was attributed to incorporation of oxygen-containing functional groups on the treated surface and concomitant reduction in fluorine as revealed by the XPS analysis and increase in surface roughness analyzed from the atomic force micrographs. Ageing upon storage in ambient air showed retention of the induced increase in surface wettability. 相似文献