Subnormal glow discharge in a Xe/Cl2 mixture in a narrow discharge tube

Electrical and optical characteristics of a subnormal glow discharge in a short (L=10 cm) discharge tube with an inner diameter of 5 mm are investigated. The dependences of the discharge current-voltage characteristic, the energy deposition in the discharge, the plasma spectral characteristics in the 130-to 350-nm wavelength range, the emission intensities of the XeCl(D-X) 236-nm and XeCl(B-X) 308-nm bands, and the total emission intensity in the range 180–340 nm on the pressure and composition of the Xe/Cl₂ mixture are studied. Two modes of glow discharge are shown to exist: the low-current mode at a discharge current of I _ch ≤2 mA and the high-current mode at I _ch >2 mA. The transition from one mode to another occurs in a stepwise manner. The increase in the chlorine content causes the discharge voltage and the energy deposition in the plasma to increase. At low pressures of the Xe/Cl₂ mixture (P≤0.7 kPa), stationary strata form in the cathode region. The lower the discharge current, the greater the volume occupied by the strata. This longitudinal discharge acts as a powerful source of continuous broadband emission in the range 180–340 nm, which forms due to overlapping the XeCl(D, B-X) and Cl ₂ ^* bands with edges at λ=236, 308, and 258 nm. The intensity of the 236-nm band is at most 20% of the total intensity of UV radiation. The maximum power of UV radiation (3 W at an efficiency of 8%) is attained at a xenon partial pressure of 250–320 Pa and a total pressure of the mixture of 2 kPa.     

The characteristics of a negative corona discharge in He/Xe/SF6 mixture

The results of investigation of the electrical and optical characteristics of a negative corona discharge in the electrode system of the type needle-grid lit in a He/Xe/SF₆ mixture under the pressure of 100–300 kPa are presented in this paper. The given medium is working for a pulse-periodic excimer lamp on = 351 nm XeF(B–X). Distributed on the length of a lamp active media a bipolar corona discharge is intended for using in the electric circulation of the XeF-lamp working medium. It is shown that the given discharge is ignited steadily in the He/Xe/SF₆ mixture, containing 0, 5kPa SF₆ molecules and is characterised by a low power consumption; the current of the discharge is limited to the development of instability by increasing the voltage on the needles; in hot zones of corona discharge SF₆ molecules cause the effective population 6s of XeI state.     

Emission from a DC glow discharge in a He/H2O mixture

The electrical and optical characteristics of a longitudinal dc glow discharge in a cylindrical discharge tube in mixtures of helium with saturated water vapor at room temperature are investigated. In the UV range, a broad band with a maximum at λ_max=309.6 nm and Δλ=9 nm prevails. The H_α 656.3-nm, H_β 486.1-nm, and HeI lines in the range 440–670 nm are the main diagnostic spectral lines. The helium partial pressure and the glow discharge current are optimized to achieve the maximum intensities of the 309.6-nm band and HeI and HI spectral lines. The results obtained are of interest for the development of an ecologically safe radiation source based on the products of the decomposition of water molecules and clusters in plasma.     

Thermal-energy Pooling Collisions in Cesium Vapor6P3/2+6P3/2→7PJ+6S1/2

In this paper, the results of an experimental study on 6P3/2+6P3/2→7PJ+6S1/2 energy pooling collisions are presented. The experiment was carried out in cesium vapor using an external cavity diode laser for excitation under different temperatures. It is found that the response of fluorescence intensity to the frequency of excitation laser shows a two-peak phenomenon.     

Electron impact ionization and excitation rate coefficients in the negative glow region of a glow discharge

Some easy to use reasonable approximations for electron impact rate coefficients have been considered. The most important rate coefficients for electron collisions in noble gases are electron-neutral ionization and electron impact excitation. Electron-neutral ionization besides electron impact excitation of some states of the argon and helium atom in direct current (dc) glow discharge plasma has been calculated. The plasma parameters of electron are significant factors for computing the rate coefficients. We present first results of probe diagnostic that includes the double probe measurements of the plasma parameters, namely, electron temperature (T_e) and electron density (n_e). Electron properties obtained from the double probe characteristic curves including T_e and n_e as well as the calculated rate coefficients (ionization and excitation) were studied as a function of the axial distance from the cathode while the discharge operating parameters of voltage and pressure were varied. Two regions of the glow discharge were investigated: cathode fall region and negative glow. Particular emphasis was placed on the negative glow region.     

大气压Ar／NH3介质阻挡辉光放电的仿真研究

为了研究火气压下氩气（Ar）中掺杂氨气（NH3）的Ar／NH3介质阻挡辉光放电的放电机理,通过建立一‘个多粒子的自洽耦合流体模型,采用有限元方法进行数值计算,得到了气体间隙压降、介质表面电荷密度、放电电流密度随时间的周期变化波形,以及带电粒子、中性粒子与空间电场强度的时空分布．仿真计算结果表明：气体间隙的周期击穿过程主要由气隙电压控制,并受气隙两侧介质极板上积聚的表面电荷的影响．气隙间带电粒子密度和电场强度的时空分布表明本文的放电过程存在阴极位降区、负辉区、法拉第暗区、等离子体正柱区等辉光放电的典型区域,放电模式为大气压辉光放电．在Ar/NH3等离子体中,主要的正离子为NH＋,其次为Ar2＋,主要的负离子为NHi：NH3分解产生的主要的激发态分子为NH,NH2和N2H3,而最终的稳态产物主要是N2和H2．     

Recombination excitation of atoms in the negative glow of a neon discharge

It is shown that under anomalous discharge conditions an important contribution to excitation of radiation in a negative glow is made by dissociative recombination, which effectively populates not only the 2p and 3p, but also the higher-lying s and d, levels.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 18–23, June, 1977.     

类铍离子1s22s2p 3P1, 2 能级之间的磁偶极跃迁

用多组态Dirac-Fock和相对论组态相互作用的扩展优化能级方法,在计算中包含了Breit相互作用,真空极化,自能以及有限核质量修正,计算了核电荷数从Z=6到80的类铍离子等电子序列的1s22s2p 3P1, 2的精细结构能级,磁偶极跃迁几率和振子强度。结果与目前可靠的结果在其不确定度范围内符合得很好,另外也得到一些与其他早期理论计算不同的结果。     

Effect of negative glow on the elementary processes occurring in the cathode region of a glow discharge

The role of the negative glow in producing charge carriers and the effect of this region on the elementary processes occurring in the region of cathode potential drop between plane parallel electrodes is considered in this paper.An estimate of the value of positive ion current passing to the cathode from the negative glow is made for nickel, copper, iron, and aluminum cathodes in hydrogen, and for an iron cathode in argon neon, and helium at 1 mm Hg pressure.Based on the values obtained for the ion current in the Crookes dark space, the electric field intensity and potential distributions are calculated and found to be in satisfactory agreement with the experimental data.     

Excitation transfer in the plasma of a barrier discharge in a krypton-xenon mixture

Processes of excitation transfer in the plasma of a barrier discharge in a krypton-xenon mixture are studied. A kinetic diagram of energy transfer is proposed, and a system of coupled kinetic equations describing the dynamics of processes in the plasma of a barrier discharge of mixtures in pure xenon as well as in a krypton-xenon mixture is composed and solved. The effect of excitation transfer on the population distribution over vibrational levels of krypton excimers excited by a barrier discharge in a krypton-xenon mixture is studied. The deviation from the equilibrium distribution over vibrational levels is found. It can be interpreted as an indication of the activation of the mechanism of depopulation of the lowest vibrational levels of excimer states of krypton.     

Photoionization cross section of Xe+ ion in the pure 5p5 2P3/2 ground level

Coupling an ion trap with synchrotron radiation is shown here to be a powerful approach to measure photoionization cross sections on ionic species relaxed in their ground state. The photoionization efficiency curve of Xe+ ions stored in a Fourier transform ion cyclotron resonance ion trap was recorded at ELETTRA in the 20-23 eV photon energy range. Absolute cross sections were derived by comparison of the photoionization yield of Xe+ with measurements from the ASTRID merged-beam experiment. Multiconfiguration Dirac-Fock calculations were performed for the interpretation of these new data.     

Population of the higher-lying vibrational levels of the nitrogen B3π state in a glow discharge

The absolute populations of the higher-lying vibrational levels of the B³ state of the nitrogen molecule in a glow discharge have been determined for pressures from 0.1 to 1.0 torr and current densities from 80 to 200 mA/cm². The absolute concentrations of molecules at levels v = 5, 6, ..., 12 under these conditions are of the order of 10⁹–10¹¹ cm^–3. The most probable processes leading to a population of the B³ state are thought to be direct electronic impact, cascade transitions, and collisions of normal molecules with molecules in the singlet state.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 2, pp. 57–63, February, 1971.