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1.
A normalized plasma flow velocity in highly collisional plasma formed by a microwave plasma jet, which is dimensionless unit for plasma flow velocity/ion acoustic velocity, was measured by the parallel Mach probe. To deduce the normalized plasma flow velocity under highly collisional plasma conditions, the collisional model of a Mach probe was proposed. In addition, neutral gas flow velocity which assumed to be plasma flow velocity was calculated by the turbulent model. The results for the two different models were compared with those for the collsionless models of the Mach probe. The turbulent model produced 2–4 times reduced values than by measurements with collsionless models. The measured results with the collisional model were shown as approximately 100–250% lower than those for collsionless models. They were obtained to be in good agreement with difference rate of 10–30% when compared to those for the turbulent model. 相似文献
2.
Emission coefficients of shock-tube plasmas have been measured as functions of the plasma parameters in the visible spectrum. The plasma state was determined by dual-wavelength interferometry and high accuracy of the ξ-factors was achieved. The results are compared with theoretical and other experimental data. In particular, the dependence of ξ on the plasma state is discussed. 相似文献
3.
This paper covers the calculation and measurement of the noise temperature for a stationary and axial homogeneous column plasma of a nitrogen discharge. The calculations are based on an electron energy distribution function which was obtained by the solution of the Boltzmann equation for a nitrogen plasma. In the low current column of this plasma the noise temperature was measured, using a Dicke-radiometer. The comparison between the calculated and measured values of the noise temperature shows a good agreement in the considered parameter region. Using a Maxwellian distribution, which was fitted to the real nitrogen plasma by the aid of the formulation of an energy balance for the electrons, the noise temperature was additionally determined in a approximate way and compared to the first calculations. 相似文献
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V. Antoni M. Bagatin A. Buffa G. Della Mea F. Freyre Jr. P. Mazzoldi F. Romanato 《Il Nuovo Cimento D》1991,13(4):435-453
To investigate the ion flux escaping from the plasma and the impurity flux released by the wall, collector probes made of
graphite, silicon and titanium have been exposed to the deuterium plasma confined in the toroidal device ETA BETA II. The
damages on the collector surfaces have been surveyed by a scanning electron microscopy (SEM) apparatus. The deuterium and
impurity retention have been measured by elastic recoil detection (ERD) and Rutherford backscattering spectroscopy (RBS) techniques
respectively. The implantation build-up has been investigated as a function of the exposure time. The deuterium dose in graphite
saturates after a few discharges, whereas the metal impurities exhibit a linear increase in time. The deuterium flux and its
radial dependence, inferred from the implanted concentrations, have been compared with those measured by Langmuir probes.
Metal impurities have been identified and their relative abundances have been compared with the material wall composition.
The impurity flux is found consistent with the global content in the plasma derived by spectroscopic measurements. The deuterium
dose measured in different samples has been related to the backscattering coefficient of the materials. Finally, to investigate
the damage on sample probes facing the plasma particle flow, erosion probes made of vitreous graphite with silver implanted
at a fixed depth have been exposed to the plasma and the thickness change after exposure recovered. 相似文献
7.
S. Helhel A. R. Ellingboe O. Cerezci C. Gaman 《International Journal of Infrared and Millimeter Waves》2006,27(11):1497-1515
Measurements of hydrogen plasma density are made in a symmetric single frequency confined capacitively coupled plasma (C-CCP)
RF system. Comparison is made between density measured by microwave interferometer (MWI) and electrode wall ion density gathered
from Ion Energy Distribution Function (IEDF) responses. Ion number density at electrode wall is obtained by two methods as
IEDF integration method and IEDF splitting method. Both methods were compared with MWI and a linear relation is obtained between
both methods and MWI. It is demonstrated that electrode wall surface density obtained by IEDF splitting and IEDF integral
methods are about 50,000 times less than the bulk plasma density, and integral method reads more data than splitting method.
The three different measurement results are compared and they are in good qualitative agreement; the deviation in ratio of
bulk plasma density measured by MWI to number density at the electrode wall resolved from ion energy distribution function
is greatest at highest pressure or electrode voltages/powers. The reasons for deviations are explained by analysis of the
potential drop across the presheath decreases with respect to increased applied power. 相似文献
8.
N. Konjević J. Labat Lj. Ćirković J. Purić 《Zeitschrift für Physik A Hadrons and Nuclei》1970,235(1):35-43
Half-widths of fifteen Stark broadened argon II lines have been measured in argon plasma behind the reflected shock wave produced in an electromagnetically driven “T” tube. The plasma electron density was determined by the laser interferometry at three different wavelengths, while the plasma temperature was measured from relative intensities of A II lines. Temperatures were in the range 8,500–16,500 °K; electron densities varied from 1.82 to 3.94 · 1017 cm?3. The measured A II linewidths are compared with theoretical and other experimental results. It is shown that a) the broadening of A II lines is in good agreement with the theory, b) line broadening increases linearly with electron density, and c) the Stark broadened lines follow the dispersion profile to the distance of at least three halfwidths from the line center. 相似文献
9.
为了对GaN薄膜低温生长提供更多的活性氮,在一个腔耦合电子回旋共振(ECR)半导体加工装置上,用朗谬探针和二次微分理论,研究了氮ECR等离子体的实际电子能量分布。发现它们都是非麦克斯韦分布,含有高能电子,而且随着放电气压的下降和微波功率的增加,高能电子成分增加。 相似文献
10.
Jung Y.K. Seo J.W. Kim Y.H. Kang B.K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2003,31(3):362-368
This paper presents a circuit model for a two-electrode AC discharge, which has two electrodes separated from the discharge gap by an insulator. The model consists of a series connection of an equivalent circuit for plasma and two capacitors for insulator. The equivalent circuit for plasma was constructed using the measured electrical properties of a two-electrode DC discharge. The validity of model was checked with experiments on a three-electrode test device; two electrodes exposed to the discharge gap and the other electrode separated from the discharge gap by an insulator. The measured voltages of the test device are compared with those obtained by circuit simulation. For various waveforms, which are being used widely to drive an AC plasma display panel, the results of circuit simulation agree well with experiment. 相似文献
11.
Zhencen He 《中国物理 B》2023,32(1):15202-015202
A study of a nanosecond laser irradiation on the titanium-layer-buried gold planar target is presented. The time-resolved x-ray emission spectra of titanium tracer are measured by a streaked crystal spectrometer. By comparing the simulated spectra obtained by using the FLYCHK code with the measured titanium spectra, the temporal plasma states, i.e., the electron temperatures and densities, are deduced. To evaluate the feasibility of using the method for the characterization of Au plasma states, the deduced plasma states from the measured titanium spectra are compared with the Multi-1D hydrodynamic simulations of laser-produced Au plasmas. By comparing the measured and simulated results, an overall agreement for the electron temperatures is found, whereas there are deviations in the electron densities. The experiment-theory discrepancy may suggest that the plasma state could not be well reproduced by the Multi-1D hydrodynamic simulation, in which the radial gradient is not taken into account. Further investigations on the spectral characterization and hydrodynamic simulations of the plasma states are needed. All the measured and FLYCHK simulated spectra are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.57760/sciencedb.j00113.00032. 相似文献
12.
准分子激光诱导铅等离子体中谱线Stark展宽时空特性研究 总被引:5,自引:5,他引:0
测定了激光诱导铅等离子体中铅原子和离子谱线Stark展宽的时间演化特性以及与缓冲气体压力之间的关系,由此计算得到了等离子体中电子密度的时间演化特性及其与缓冲气体压力之间的关系,实验结果表明,由不同的金属固体材料产生的激光等离子体的动力学性质差异很大,并讨论了形成这种差异的物理机制。 相似文献
13.
Two-dimensional maps of atomic hydrogen concentration in reactive gas layers were measured using two-photon laser-induced
fluorescence. The measurements were made in conditions of diamond-film chemical vapour deposition using a thermal inductively
coupled plasma. Their purpose was to investigate the influence of the atomic hydrogen concentration in the reactive gas layer
on the diamond growth. Concentration maps were obtained under parametric variation of the plasma flow conditions. Axial profiles
were extracted from the measured maps and compared to temperature profiles measured by Rayleigh scattering to determine the
degree of chemical non-equilibrium in the reactive layer. The non-uniform quenching over the measured area was accounted for
with an iterative calculation of the species concentrations. For small differences of the atomic hydrogen concentration in
the reactive layer a large variation in quality of the grown diamond was observed.
Received: 28 June 2000 / Revised version: 6 October 2000 / Published online: 21 February 2001 相似文献
14.
Electron diamagnetic effect on axial force in an expanding plasma: experiments and theory 总被引:1,自引:0,他引:1
The axial force imparted from a magnetically expanding current-free plasma is directly measured for three different experimental configurations and compared with a two-dimensional fluid theory. The force component solely resulting from the expanding field is directly measured and identified as an axial force produced by the azimuthal current due to an electron diamagnetic drift and the radial component of the magnetic field. The experimentally measured forces are well described by the theory. 相似文献
15.
Dubin DH 《Physical review letters》2005,94(2):025002
An analogy is uncovered between the nuclear reaction rate in a dense neutral plasma and the energy equipartition rate in a strongly magnetized non-neutral plasma. In strong magnetic fields, cyclotron energy, like nuclear energy, is released only through rare close collisions between charges. The probability of such collisions is enhanced by plasma screening effects, just as in nuclear reactions. Enhancements of up to 10(10) are measured in simulations of cyclotron energy equipartition and are compared to the theory of screened nuclear reactions. 相似文献
16.
Hyung Jin Kim Sang Hee Hong 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1995,23(5):852-859
The ion and electron temperatures and plasma flow velocities are measured and compared between atmospheric and low pressure plasma spraying systems. The measurements of ion temperature for two systems are carried out by an optical emission spectroscopy which uses the relative emissivities of isolated Ar I emission lines. The electron density and temperature are measured by a Langmuir probe rotating across the plasma jets. The ion saturation currents collected by a Mach probe at two orientations, perpendicular and parallel to the plasma jet, determine the flow velocity. The spatial distributions of electron density, plasma flow velocity, and the associated shock activity in thermal plasma jets are discussed in conjunction with their direct dependency upon the ambient pressures as well as the torch powers. Measurements on temperatures and velocity profiles of thermal plasma jets reveal the general features of the LPPS jet characteristics, i.e., higher velocity flow with lower temperature, longer heating zone of expanded flame, and more extended accelerating zone compared with those of the APS jets. The shock activity clearly exists in the form of standing shock waves in the plasma jet of LPPS in view of flow compression and abrupt velocity drop which are appeared in the results of measurements on the variations of electron density and flow velocity along the plasma jet. In the center of the plasma jet of APS, the electron density is high enough to reach the LTE criterion, and the difference between ion and electron temperatures becomes insignificant as the torch input power increases 相似文献
17.
Experimental results on the measurement of current collected by an electrode immersed in a plasma for a pulsed negative bias
are presented. The measured current is compared with a model based on the concept of an expanding capacitor. The scaling laws
predicted by the model are verified for the measured current which agree each other. The paper emphasizes the role of displacement
current in an expanding ion sheath. 相似文献
18.
Conde L. Leon L. Ibanez L.F. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1997,25(4):548-552
The electron transport properties of plasma clouds generated by a hollow cathode discharge are investigated. The voltage-current characteristic curves indicate that the electron-emitted electron current depends on both bias voltage and discharge current. The spatial dependence of the electronic density, plasma potential, and electronic temperature is measured. The energy loss rate of a high energy group of electrons with the radial distance is also presented. These experimental results are compared with a nonisothermal transport model which reproduces the spatial dependence of plasma properties 相似文献
19.
Yoshiaki Hattori Shinobu Mukasa Hiromichi Toyota Shinfuku Nomura 《Current Applied Physics》2013,13(6):1050-1054
The electrical breakdown of microwave plasma in water was investigated between 1 and 30 kPa. The dependency of the ignition power for generating plasma on the size of coaxial electrode was measured. The ignition power decreases with a decrease of the diameter of the inner electrode. The behavior of microwave plasma in water was observed using a high-speed camera. The plasma ignites in a bubble generated by microwave heating. The model for calculating the electric field was created on the basis of the captured images of the bubble just before plasma ignition. The method presented can be used to visualize the electrical field distribution in the bubble. The electric field breakdown was calculated using the measured ignition power. The electric field breakdown of plasma in water is of the same order as gas phase plasma. 相似文献
20.
S. I. Gubarev A. A. Dremin V. E. Kozlov V. M. Murav’ev I. V. Kukushkin 《JETP Letters》2009,90(7):539-543
The dispersion of magnetoplasma and plasma excitations in two-dimensional electron systems, whose edges are formed by a voltage
applied to a metallic gate, has been studied. A substantial decrease in the plasma wave frequency as compared to the plasma
frequency measured in the etched mesas with the same geometry, size, and electron density has been observed. The dependence
of the observed frequency softening on the structure size has been studied and the laterally screened plasma excitation has
been shown to violate the square-root dispersion relation. 相似文献