摘要:

AbstractSpatially resolved plasma induced emission spectroscopy (PIE) is applied to a symmetric parallel plate discharge in helium under rf excitation at 13.56 MHz. The optical emission features are studied in the pressure range of 10–360 Pa and power densities from 6 mW/cm3to 90 mW/cm3. At pressures above 60 Pa and power densities exceeding 50 mW/cm3the transition from the α‐ to the γ‐mode is observed, which, in helium, is accompanied by the formation of a disk‐shaped brightly luminous glow. A marked difference between the emission from levels of the triplet and singlet system of the helium atom occurs above this threshold of applied power. The spatial emission distribution of equivalent lines of the helium atom is rather different under pressure variation. Therefore the spatial distribution of the metastable levels is concluded to be substantially different between singlets and triplets. This effect is attributed to a rapid decrease of electron temperature and increase of electron density which is a characteristic of the transition between the two heating modes. Low temperature and high density of the electrons favour an overproportional growth of the associated 21Sdestruction rate, i.e., singlet to triplet conversion. A similar effect has been reported for a dc discharge by Lawler e

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330302

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe behaviour of gas discharges can be modelled by equivalent circuits built on the basis of a theoretical description of the plasma. This paper introduces a method to develop a nonlinear equivalent circuit directly by means of the balance equations of the column plasma and by the help of the knowledge obtained from the design of the linear equivalent circuit. The linear network theory was used for the derivation. The circuit found in this way is similar to a derived linear equivalent circuit of the column plasma with two inertial factors (delayed effects) for a neon gas discharge described in previous papers.

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330303

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe homogeneity and stability of TEA‐Excimer laser discharges strongly depend on the preionization. A homogeneous discharge can only develope if it is ensured that the electron density exceeds a certain level at the moment of the ignition. The kinetic of these electrons during the preionization is analyzed theoretically by the use of the Boltzmann equation for x‐ray preionized KrF* laser systems. The time dependent velocity distribution of the electrons is calculated for different buffer gases and gas mixtures. The resulting electron densities and life times are discussed and compared with experimental investigations. It is quantitatively shown at the first time that the kind of the buffer gas has a decisive influence on the velocity distribution, density and life time of the preionization electr

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330304

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractStark shifts and widths of ionized boron, carbon and nitrogen spectral lines have been measured in a low‐pressure pulsed arc plasma and compared with calculated values based on the modified semiempirical approac

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330305

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractCathode spots of vacuum arcs on pre‐arced surfaces have been studied using image converter photographs with suitable temporal and spatial resolution. Part I describes experimental details and presents observations of two coexisting spot modes: the smaller spots tend to move behind the larger spots. A possible relationship to the general classification scheme for arc cathode phenomena (Anders and Anders, 1989) is discusse

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330306

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractAn extended eigenvalue problem for collisionless electrostatic driftwaves in cylindrical and slab geometry is discussed and solved in local approximation. The fact of a minimum threshold for the ITG instability (ηi‐mode) is used to get a unique concept for profile determinati

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330307

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe problem of stability of a self‐gravitating, infinite homogeneous gas in the presence of magnetic field is investigated. The medium is assumed electrically and thermally conducting. The effect of porosity, electrical conductivity, thermal conductivity and Hall current is investigated on the self‐gravitating plasma flowing through porous medium. The relevant linearized equations of the problem are stated and dispersion relation is obtained. The effect of Hall current on the condition of the instability of the system is examined for both longitudinal and transverse mode of propagation and found that in longitudinal propagation Hall effect does not change the condition of instability but modifies the Alfvén wave mode. The stability of the system is discussed by applying Routh‐Hurwitz criterion and it is found that Jeans criterion determines the stability of the system. Thermal conductivity and porosity have a destabilizing influence on the medium. The general condition for instability of the system is also d

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330308

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThis report presents a theoretical model of extraordinary mode radiation in presence of low frequency whistler mode. We show that the generation mechanism of extraordinary mode emission in the presence of whistler mode is based on the plasma maser theory. Application of theoretical results to Jovian Kilometric radiation is examined.

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330309

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330301

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY