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1.
A Power Interruption Technique for Investigation of Temperature Difference in Stabilized Low Direct-Current Arc Burning in Pure Argon on Atmospheric Pressure
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M. M. Kuzmanovic J. J. Savovic D. P. Rankovic M. Stoiljkovic A. Antic Jovanovic M.S. Pavlovic M. Marinkovic 《中国物理快报》2008,25(4):1376-1379
Plasma of argon stabilized arc column, in a current range 3-11 A, is investigated using emission spectrometric diagnostic techniques. Temperatures are evaluated using several methods: argon line to adjacent recombinational continuum intensity ratio, absolute emissivity of argon line, measurement of electron number density, and power interruption. Electron number density is evaluated from absolute emissivity of recombinational continuum. The difference between electron Te and heavy particle Th temperature ranged from 4500 K for 3 A to 2300 K for 11A arc current. By comparing the present with the previously obtained results, using the same arc device but with the introduction of water aerosol, it is concluded that water aerosol reduces the difference Te - Th and brings plasma closer to the partial thermodynamic equilibrium state. 相似文献
2.
Arc root motions in generating dc argon hydrogen plasma at reduced pressure are optically observed using a high-speed video camera. The time resolved angular position of the are root attachment point is measured and analysed. The arc root movement is characterized as a chaotic and jumping motion along the circular direction on the anode surface. 相似文献
3.
M. K. Mishra A. Phukan M. Chakraborty K. S. Goswami 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(2):303-306
This paper reports about the observed energy growth of
both high and low energetic electron species in the target plasma region
with the increase in plasma potential in the source region of a double
plasma device. This situation can be correlated to the injection of an ion
beam from source to target plasma region. Plasma is solely produced in the
source region and a low-density diffuse plasma is generated in the target
region by local ionization between the neutral gas and the high energetic
electrons coming from the source region. The growth of electron energy is
accompanied by a decrease in diffuse plasma density. It is observed that
although energy of high energetic group increases with the injected beam
energy, the diffuse plasma density falls due to their decreasing population. 相似文献
4.
A hot particle jet is induced as a laser pulse from a free oscillated Nd:YAG laser focused on a coal target. The particle jet successfully initiates combustion in a premixed combustible gas consisting of hydrogen, oxygen, and air. The experiment reveals that the ionization of the particle jet is enhanced during the laser pulse. This characteristic is attributed to the electron cascade process and the ionization of the particles or molecules of the target. The initial free electrons, which are ablated from the coal target, are accelerated by the laser pulse through the inverse Bremsstrahfung process and then collide with the neutrals in the jet, causing the latter to be ionized. 相似文献
5.
Micron size dust particles were used to diagnose the direction of ion flow in an inertial electrostatic confinement discharge. Particles were dropped onto a one-dimensional device and were shown to deflect away from the center. The deflection of the dust particles was then accounted for by ion drag. It is concluded that ions are created at the cathode center and flow outwards. This supports recent work that has reached the same conclusion using Doppler spectroscopy. Moreover, estimates of the ion density from the deflection of dust particles was in agreement with Langmuir probe measurements. 相似文献
6.
After getting charged in plasma, dust grains in a dust beam are scanned by a Faraday cup and electrometer. At different operating conditions, including a dc field, and analysis of the dust current profile, dust charge distribution is studied and information on the nature of the nonuniform distribution obtained. 相似文献
7.
Theoretical and Experimental Study of Scattering of a Plane Wave by an Inhomogeneous Plasma Sphere
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Scattering of electromagnetic waves by an inhomogeneous plasma sphere has been studied theoretically and experimentally. The offset angles of electromagnetic waves caused by the plasma sphere have been observed experimentally. The effects of the electromagnetic wave frequency and plasma density on the offset angle are discussed. The plasma density is estimated with the offset angle. 相似文献
8.
The influence of Exciting Frequency on N2 and N2+ Vibrational Temperature of Nitrogen Capacitively Coupled Plasma
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By using optical emission spectroscopy (OES), N2 and N2^+ vibrational temperatures in capacitively coupled plasma discharges with different exciting frequencies are investigated. The vibrational temperatures are acquired by comparing the measured and calculated spectra of selected transitions with a least-square procedure. It is found that N2 and N2^+ vibrational temperatures almost increase linearly with increasing exciting frequency up to 23 MHz, then increase slowly or even decrease. The pressure corresponding to the maximum point of N2 vibrational temperature decreases with the increasing exciting frequency. These experimental phenomena are attributed to the increasing electron density, whereas the electron temperature decreases with exciting frequency rising. 相似文献
9.
* fluorescence radiation from the ion–ion recombination process in the gas volume during the preionization phase, therefore
allowing spatial resolution by partial imaging of the volume. Volume-integrated and temporally resolved measurements are carried
out to determine the average of absolute preionization densities by comparison with a theoretical model of the temporal behaviour
of the recombination process. Spatially resolved measurements reveal the distribution of the preionization density. The preionization
densities determined from spark and sliding/corona discharges schemes are considerably higher (ne
0?1012 cm-3) than those obtained from pulsed X-ray preionization (ne
0?107 cm-3).
Received: 3 October 1997/Revised version: 6 January 1998 相似文献
10.
Optical Emission Spectroscopy Investigation of a Surface Dielectric Barrier Discharge Plasma Aerodynamic Actuator
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The optical emission spectroscopy of a surface dielectric barrier discharge plasma aerodynamic actuator is investigated with different electrode configurations, applied voltages and driving frequencies. The rotational temperature of N2 (C^3 Ⅱu) molecule is calculated according to its rotational emission band near 380.5 nm. The average electron energy of the discharge is evaluated by emission intensity ratio of first negative system to second positive system of N2. The rotational temperature is sensitive to the inner space of an electrode pair. The average electron energy shows insensitivity to the applied voltage, the driving frequency and the electrode configuration. 相似文献
11.
Research of Plasma Characteristics of the Radio-Frequency Discharge in O2 and Its Mixtures
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Electron mean energy and the effects of gas mixture are studied theoretically and experimentally. The electron mean energy in O2 and its mixtures is obtained by solving Boltzmann's equation. The experiments of the Langmuir probe system and spectral analysis are carried out. It is shown that electron temperature goes down with the increasing pressure, narrowing pulse width and the addition of helium and argon. According to the intensity of oxygen atom at 777.19 nm, xenon is more effective in inhibition of O2 decomposition than helium and argon. 相似文献
12.
T. Hammer 《Applied physics. B, Lasers and optics》1993,56(5):243-248
The small signal gain, amplified spontaneous emission and laser spectra of a transverse discharge-excited XeCl laser have been measured. Several gas mixtures, total gas pressures and electron densities have been investigated. From these measurements it is concluded, that bound-free transitions and transitions to high-lying vibrational levels of the ground state contribute significantly to the gain and laser emission. For the upper laser level a vibrational population ratio [XeCl(B, =1)]/[XeCl(B, =0)] corresponding to a temperature of about 370 K has been determined. The intensity ratio of about 1 observed for the two laser lines may be explained by the vibrational and quenching kinetics of the lower laser level together with the upper state kinetics. A table summarizing the result of the small gain measurement has been included for model comparison. 相似文献
13.
G. Kühn F. Könemann M. Kock 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,105(1):102-110
We perform quantitative optical emission spectroscopy on the hot core of the cathode region of a free-burning arc in argon under atmospheric pressure. As the peak temperatures in the centre of the discharge exceed 22 000 K we are able to observe three spectra of argon (Ar I, Ar II and Ar III) and the continuum emission. We report on some inconsistencies concerning the evaluation of Ar III radiation in both line and continuum emission. These are caused by erroneous data in the literature and common misconceptions about the influence of Ar III on the plasma emission. We discuss the impact of this fact on published data. 相似文献
14.
Plasma Bragg grating (PBG) is composed of periodic variations of plasma and dielectric or vacuum. The defect mode characteristic of the PBG with a cavity-defect is studied by one-dimensional particle-in-cell (1D PIC) simulation. It is shown that the laser pulse with the defect frequency can be localized around the defect partly and at the same time leak out of both sides of the grating slowly because of the few number of the grating period. This results in local high laser field intensity and high plasma density produced at the defect area, from which the third harmonic is enhanced by one order of magnitude. With the enhancement of the light coupled to the defect and the decrease of the light leaking out of the defect, the conversion efficiency of the third harmonic from the incident laser can be increased. 相似文献
15.
A. V. Karelin M. S. Stefanova P. M. Pramatarov S. I. Yakovlenko 《Applied physics. B, Lasers and optics》1993,57(4):293-300
A theoretical study of a He-Kr laser (KrII, 469.4 nm line) pumped by a helical hollow cathode discharge is presented. A detailed kinetic model of plasmachemical reactions and radiative processes including the influence of gas heating on the active medium is developed. In the process of numerical calculations the dependence of the plasma parameters (electron and gas temperature, electron and metastable density, upper and lower laser level density) and laser characteristics (output power and gain coefficient) on the variations of discharge pumping, gas-mixture partial pressures and geometry of the coil hollow cathode, are investigated. The results of the numerical calculations are in a good agreement with the experimental data. 相似文献
16.
Diagnosis of Multiple Gases Separated from Transformer Oil Using Cavity-Enhanced Raman Spectroscopy
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The Raman signal of gas molecules is very weak due to its small scattering cross section. Here, a near-confocal cavity-enhanced Raman detection system is demonstrated. In the cavity, a high power light of 9W is achieved by using a cw 200mW 532nm laser, which greatly enhances the detection sensitivity of gas species. A photomultiplier tube connected to a spectrometer is used as the detection system. The Raman spectra of the mixed gases separated from transformer oil has been observed. The relationship of absolute Raman intensity and gas pressure is also obtained. To our knowledge, this is the first Raman system to detect the gases separated from transformer oil. 相似文献
17.
Diagnosis of Methane Plasma Generated in an Atmospheric Pressure DBD Micro-Jet by Optical Emission Spectroscopy
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Diagnosis of methane plasma, generated in an atmospheric pressure dielectric barrier discharge (DBD) microplasma jet with a quartz tube as dielectric material by a 25 kHz sinusoidal ac power source, is conducted by optical emission spectroscopy (OES). The reactive radicals in methane plasma such as CH, C2, and Ha are detected insitu by OES. The possible dissociation mechanism of methane in diluted Ar plasma is deduced from spectra. In addition, the density of CH radical, which is considered as one of the precursors in diamond-like (DLC) film formation, affected by the parameters of input voltage and the feed gas flow rate, is emphasized. With the Boltzmann plots, four Ar atomic spectral lines (located at 675.28nm, 687.13nm, 738.40nm and 794.82nm, respectively) are chosen to calculate the electron temperature, and the dependence of electron temperature on discharge parameters is also investigated. 相似文献
18.
U. Czarnetzki D. Luggenhölscher H.F. Döbele 《Applied Physics A: Materials Science & Processing》2001,72(5):509-521
Temporally and spatially resolved measurements of the electric field distribution in the sheath region of RF and dc discharges
provide a detailed insight into the sheath and ion dynamics. The electric field is directly related to the sheath ion and
electron densities, the sheath voltage, and the displacement current density. Under certain assumptions also the electron
and ion conduction current densities at the electrode, the ion current density into the sheath from the plasma bulk, the ion
energy distribution function, and the power dissipated in the discharge can be inferred. Furthermore, the electric field distribution
can give an indication of the collision-induced conversion between different ion species in the sheath. Laser spectroscopic
techniques allow the noninvasive in situ measurement of the electric field with high spatial and temporal resolution. These
techniques are based on the spectroscopic measurement of the Stark splitting of Rydberg states of helium and hydrogen atoms.
Two alternative techniques are applied to RF discharges at 13.56 MHz in helium and hydrogen and a pulsed dc discharge in hydrogen.
The measured electric field profiles are analyzed, and the results discussed with respect to the ion densities, currents,
energies, temporal dynamics and species composition.
Received: 26 July 2000 / Accepted: 12 December 2000 / Published online: 3 April 2001 相似文献
19.
J. Mentel 《Applied Physics A: Materials Science & Processing》1977,14(4):361-366
The root of an argon are was stabilized by strong cooling of the graphite cathode; both the composition and the temperature
of the plasma at the arc root were determined spectroscopically. The measurements of the absolute intensities of two CI and
two CII lines revealed that the plasma is composed almost entirely of atomic carbon. Immediately in front of the cathode a
temperature of 12000 K was measured and the degree to which the gas was ionized was found to be 30%. The velocity of the plasma
was 300 m/s.
This work is based upon material presented in the final report “Basic research programme for plasma technology, high-pressure
arcs in SF6” to the Federal Department of Research and Technology, Fed. Rep. Germany. 相似文献
20.
Influence of Substrate on the Transportation Properties of Co/Alq3 Granular Films on a Si Wafer
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A series of Co0.48 (Alq3)0.52 granular films were deposited on silicon substrates using the co-evaporating technique. A crossover of magnetoresistance (MR) from negative to positive was observed in the samples, due to conducting channel switching. The transport properties of samples are greatly influenced by hydrofluoric acid pretreatment, as a result, positive MR decreases drastically and the temperature dependence of resistance changes a lot near room temperature. The result indicates that the native oxide layer plays an important role in the transport mechanism. Moreover, different resistivities of Si substrates influence the current distribution of conducting channels, leading to different transport behaviors accordingly. 相似文献