共查询到20条相似文献,搜索用时 647 毫秒
1.
E. Kranz 《等离子体物理论文集》1982,22(3):221-233
An electric arc quickly moved magnetically forms a closed plasma cone or plasma ring between two concentrically arranged electrodes. Aerosols and suspended matters can be brought into the plasma in an optimum manner with a little carrier gas flow, and can be excited to emission. The dates applied and attained till now are: Arc current 5…?20 A, magnetic field strength 104…?4 · 105 A/m, magnetic induction 0.1…?0.3 T, rotation frequency 8…?15 kc, carrier gas air or argon maximum flow 0.5 1/min, intensity increase for CuI-lines up to factor 100. Further applications are possible for special lamps and electric arc diagnostics. 相似文献
2.
D. S. Munkhoz V. A. Bityurin A. I. Klimov P. N. Kazanskii I. A. Moralev L. B. Polyakov B. N. Tolkunov 《Technical Physics》2017,62(7):1013-1018
The structure and dynamics of a near-wall gas flow produced by a rotating electric arc discharge in an external magnetic field around a cylindrical model without an incoming flow has been investigated. The electric arc on the model has been produced by a combined electric discharge (low-current rf discharge + high-current pulse-periodic discharge). Permanent magnets with induction B ≈ 0.1 T have been placed inside the cylindrical models. Ring electrodes are arranged on the surface of the model. The structure and dynamics of the near-wall gas flow around the cylindrical model have been investigated using high-speed photography, as well as the shadowgraph and particle image velocimetry (PIV) methods. 相似文献
3.
The structure, composition, and electrocatalytic properties of the coatings formed on aluminum by ion-beam-assisted deposition
of platinum from the plasma of a pulsed arc discharge under conditions where deposited-metal ions are used as deposition-assisting
ions are studied. The coating thickness reaches ~30 nm, and the near-surface content of platinum atoms in the coatings is
~2.6 × 1016 cm-2. The electrocatalytic activities of aluminum-based electrodes with the coatings in the reactions of electrochemical oxidation
of methanol and ethanol, which form the basis for the principle of operation of low-temperature fuel cells (considered as
promising chemical sources of an electric current), are significantly higher than the activity of a platinum electrode. 相似文献
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5.
The spectroscopic diagnostics has been carried out as an example for an argon plasma from Maecker-Shumaker type electric arc supplied by periodic variable current. It is shown that the time-dependent runs of intensity of the plasma light may be determined using an ordinary oscilloscope. We have stated that the electron concentration Ne in the plasma is the most sensitive quantity to the current pulsations. In the percentage, Ne variations at the arc axis are approximately the same as the current ones. 相似文献
6.
E.G. Gurvich 《Physics letters. [Part B]》1979,87(4):386-388
We assume that pairs in a quark jet are generated similarly to e+e? pairs in a constant uniform electric field. In this way we obtain relative yields and a lower bound for the average transverse momenta (ATM) of all quark flavors. In particular, the ATM of strange quarks would be larger than those of nonstrange ones. From an analysis of the mass dependence of the widths of the parent-trajectory hadrons an estimation of the radius of the colour electric field tube is obtained. 相似文献
7.
Experimental and theoretical investigations have been performed to determine the thermal conductivity of hydrogen in the temperature range between 2000 and 7000 °K. For this purpose the radial temperature distributions for various currents and theE-I-characteristic of a low current wall-stabilized hydrogen arc have been measured. In the dark region of the arc outside the bright core the temperature and the thermal conductivity between 2000 and 4500 °K were found by means of the schlieren technique. The electron temperature in the core of the arc results from spectroscopic measurements. The gas temperature has been calculated with a formula, derived from the kinetic theory of gases. Assuming a constant collision integralQ eH 11 the radial distribution of electric conductivity has been calculated according to Langevin's formula. The valueQ eH 11 =30·10?16 cm2 results by comparing the integrated conductance with the measured one. Since now the radial distribution of power input and the temperatures are known, the thermal conductivity between 4500 and 7000 °K can be determined as well. The total course of the heat conductivity shows a strong peak at the temperature of 3740 °K characteristic for the dissociation process. 相似文献
8.
The developed general physical-mathematical model, FEM-based calculation procedure as well as the software were in practical
use to simulate the processes of the non-stationary conjugate heat exchange and phase transformations during the processing
of the surface with a high-concentrated energy fluxes, with a stationary, pulsed, and movable heating sources (the processing,
including the surface fusing with a quasilaminar plasma jet, transfer electric arc and impulse electron beam; cleaning of
the metal substrate surfaces from an oxide layer with the aid of a cathode vacuum arc, etc). The processes of practical importance
with considerably different spatial and temporal scales featuring the density of the heat fluxes power q ∈ [107; 1014] W/m2 have been studied.
The work was financially supported by the Russian Foundation for Basic Research (Grant No. 07-08-00209). 相似文献
9.
Dayonna P. Park Kevin Davis Samid Gilani Christal-Anne Alonzo Danil Dobrynin Gary Friedman Alexander Fridman Alexander Rabinovich Gregory Fridman 《Current Applied Physics》2013
Water quality, mineralization, and chemical composition, particularly pH and nitrogen compounds each, play a crucial role in plant development and growth. Treatment of water with non-equilibrium discharges results in the change of its properties and chemical composition, which in turn may affect plant growth process and subsequently agriculture produce quality. Both thermal and non-thermal discharges generated in air or in water produce a number of reactive neutral and charged species, electric fields, and ultraviolet radiation. Plasma treatment of water results in significant change of its properties like pH, oxidation–reduction potential (ORP), conductivity, and concentration of reactive oxygen and reactive nitrogen species (ROS and RNS). Here we report the results of an experimental study of the effect of water treated with different atmospheric plasmas on germination, growth rates, and overall nutritional value of various plants. In the study we have used three types of plasmas: thermal spark discharge, gliding arc discharge, and transferred arc discharge. It is shown that the effects of these plasmas on chemical composition of various types of water are qualitatively different. Non-thermal gliding arc discharge plasma results in lower (acidic) pH, and production of significant amount of oxidizing species (e.g. H2O2). Gliding arc discharge also causes significant acidification of water, but it is accompanied by production of reactive nitrogen species (NO, NO2? and NO3?). Spark discharge treatment results in neutral or higher (basic) pH depending on initial water composition, and production of RNS. 相似文献
10.
Barengolts S.A. Mesyats G.A. Chentsov A.G. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1999,27(4):817-820
Based on the ecton model, a statistical method for studying the processes in the cathode spot of a vacuum arc has been proposed. It has been demonstrated that the spontaneous extinguishing of a DC arc and the effect of “current chopping” inherent in an AC arc are due to the cellular structure of a cathode spot and by the finite lifetime of an ecton. The principal characteristics that are responsible for the stability of the arc operation are the current per cell and the efficiency of the recovery mechanism. The average operative time of the discharge is longer for the materials showing lower currents per cell. The influence of the conditions of arc operation, such as the parameters of the external electric circuit, the cathode surface condition, the presence (or absence) of an external electric field, etc., is reduced in the main to a change in the efficiency of the recovery mechanism 相似文献
11.
F. von Gynz-Rekowski G. Ganteför Y. D. Kim 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):81-84
Interactions between oxygen and Pd cluster anions were
studied using Time-of-Flight (ToF) mass spectrometry and Ultraviolet
Photoelectron Spectroscopy (UPS). In contrast to the coinage metal clusters,
no pronounced size selectivity towards chemisorption of oxygen molecules can
be observed for the Pd cluster anions: regardless of the cluster size, no
more than 2 oxygen molecules can be attached to a cluster. When
PdnOm
- clusters are prepared by pre-dissociation of oxygen
molecules by electric arc and post-reaction with Pd, the proportion of Pd
cluster anions reacted with oxygen does not much change compared to the case
of the reaction between Pd cluster anions and O2 molecules. This result
indicates that the O2 chemisorption on Pd cluster anions does not
involve large activations barriers: using different synthesis method of a
cluster, one can get a better insight into the chemisorption routes of
molecules on metal clusters. 相似文献
12.
Drift equations of motion are derived for a charged particle in the case of a strong electric field with allowance for relativistic effects of order v2/c2. The role of these effects is discussed along with the effects of a high-frequency field. The cases of weak and strong electric fields are distinguished [2] in the drift theory of the motion of charged particles in weakly inhomogeneous magnetic and electric fields. In the case of a weak electric field, the electric-drift velocity is vE v, where v is the characteristic velocity of the particle. For a strong electric field,v
Ev.The drift theory has now been reasonably well developed for the case of weak electric fields in the classical and relativistic cases, for the absence of high-frequency fields and for the presence of these [1–3], Extension of the theory to strong electric fields involves considerable mathematical difficulties, and this has been done only in the classical approximation with and without hf fields [2–4], Here we consider the drift theory of charged-particle motion for the case of a strong electric field in the weakly relativistic approximation, incorporating terms of order v2/c2, where c is the velocity of light. Also hf fields may be present.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 7–9, September, 1981. 相似文献
13.
The behavior of an electric arc in a magnetic field is studied theoretically and experimentally. It is found that the arc behavior can be governed by the ponderomotive interaction of the arc with current-carrying elements. In a nonuniform magnetic field, the behavior of the arc depends on the Hall currents and the diamagnetic properties of its plasma. It is shown that the position of the arc channel between the end faces of cylindrical electrodes can be controlled by nonuniform magnetic fields. The methods and devices considered in this paper allow one, in particular, to control arc heat sources used in the heat treatment of metals. 相似文献
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15.
电弧增材成形常采用单道多层或多道搭接的熔积方式,不同的熔积方式下对应的熔积层表面形貌不同,从而影响电弧的形态及其传热传质过程.本文建立了纯氩保护电弧增材成形的电弧磁流体动力学三维数值模型,以及不同表面形貌的熔积层模型,并在保持阳极与阴极之间距离和熔积电流不变的条件下,通过模拟计算获得增材成形特有的单道和多道搭接熔积条件下的不同表面形貌对应的电弧形态以及相应的温度场、流场、电流密度、电磁力、电弧压力分布.数值模拟结果表明:平面基板上起弧情况下电弧中心具有较高的温度、速度、电流密度以及压强;单道多层熔积情况下熔积层数对电弧的各个参量影响较小;多道搭接熔积情况下电弧呈非对称分布,电弧中心温度较前两者低,电流密度、电磁力和电弧压强的分布偏向熔积层一侧. 相似文献
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17.
S. Anders 《等离子体物理论文集》1986,26(6):413-421
The cathode spot plasma of a metal vapour are in vacuum has a high density (1025–1028 m3) with a relatively low temperature (1–5 eV), therefore it is strongly non-ideal. The degree of ionization α and the electric conductivity σ of such plasmas are discussed, considering that non-ideality. The burning voltage of the arc UB is estimated with the help of σ-values, obtained from theories and measurements for non-ideal copper plasmas. It is shown, that a high current density of the cathode spot of j = 1012 A/m2 is not in contradiction to a low burning voltage UB = 20–30 V, but these values give a consistent picture of the spot processes. 相似文献
18.
Charge injection process from metal electrode to a
nondegenerate polymer in a metal/ polymer/ metal structure has been
investigated by using a nonadiabatic dynamic method. We
demonstrate that the dynamical formation of a bipolaron
sensitively depends on the strength of applied electric field, the
work function of metal electrode, and the contact between the
polymer and the electrode. For a given bias applied to one of the
electrode (V0) and coupling between the electrode and the
polymer (t′), such as V0=0.79 eV and t′=1 eV,
the charge injection process depending on the electric field can
be divided into the following three cases: (1) in the absence of
the electric field, only one electron tunnels into the polymer to
form a polaron near the middle of the polymer chain; (2) at low
electric fields, two electrons transfer into the polymer chain to
form a bipolaron; (3) at higher electric fields, bipolaron can not
be formed in the polymer chain, electrons are transferred from the
left electrode to right electrode through the polymer one by one
accompanying with small irregular lattice deformations. 相似文献
19.
Two types of contracted arc discharge are investigated with a view to generating intense electron beams over a wide pressure range (1–10–3 Pa). For an arc discharge with a hollow cathode and anode, an electron beam corresponding to a current of up to 300 A and a pulse length of 25 µsec is obtained at a pressure of 1–10–1 Pa in the accelerating gap with an accelerating voltage of up to 15 kV. At pressures of 10–2–10–3 Pa, emitting plasma is created by a low-pressure arc discharge on the basis of a Penning cell. Three discharge systems operating in parallel are used to increase the working life of the cathode and improve the current density distribution of the beam. An electron beam of diameter 200 mm with a current of up to 125 A and a pulse length of 50 µsec is obtained.Institute of High-Power Electronics, Siberian Branch, Russian Academy of Sciences. Translated from Izvestiya Vysshkikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 76–82, March, 1994. 相似文献
20.
Variation of parameters of a reflex discharge with a hollow cathode operating continuously in propane with a flow rate of
1.3–5.6 (m3 mPa)/s and a discharge current of 0.1–0.4 A is analyzed. It is shown that for a hydrocarbon flow rate of 2.4 (m3 mPa)/s and higher, an increase in the discharge voltage takes place after a time interval depending on the discharge current
and gas pressure; this is explained by the formation of coating of the dissociation products of hydrocarbon molecules on the
electrodes of the discharge chamber. An increase in the thickness of the carbon coating of the cathodes with time and their
charging with ions lead to electric breakdown of coatings and the formation of cathode spots. The oscillograms of the discharge
current and voltage indicate a short-term transformation of the glow discharge into the arc discharge. The energy spectra
of ions emerging from the discharge are measured, and the effect of the discharge current and the gas flow rate on the energy
spread of ions is analyzed. The operation time of the discharge in hydrocarbon after which the cleaning of the discharge chamber
is required is determined. The possibility of using an ion source based on the reflex discharge with a hollow cathode for
technological purposes is established. 相似文献