摘要:

AbstractInvestigations in a periodically driven neon glow discharge show that the occurrence of bestabilities can lead to chaotic states. These states are caused by wave phenomena. Characterizing this behaviour by means of the autocorrelation and the crosscorrelation function without the knowledge of the power spectra can imply false interpretations. These are due to the different dissipation of the fluctuations synchronous with the phase‐shifted excitation. It is demonstrated that much information obtained from a large set of data is needed for a reliable evaluation of the dynamics of chaotic state

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330202

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractA nonlinear Schrödinger equation which governs the slow modulation of high‐frequency surface waves is derived. This evolution equation is obtained from a nonlinear dispersion relation, derived for a weakly nonlinear semi‐infinite cold plasma, where effects of the finite transition layer are taken into account. The fact that the surface wave frequency coincides with the local plasma frequency somewhere inside the transition layer results in a strongly peaked electric field and a significant modification of previously derived dispersion relations assuming a sharp boundary. The consequences of the weakly nonlinear assumptions are discu

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330203

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractA one‐dimensional continuum model is presented for a dc‐glow‐discharge in an electronegative gas between parallel plates. It is based on the local balance equations for particle densities and fluxes of electrons, positive and negative ions, the local electron energy balance and the Poisson equation for the self‐consistent electric field. These equations are supplemented by suitably chosen boundary conditions and are solved by the finite difference procedure HEMODES (HEnyey Method Ordinary Differential Equation Solver) which, in particular, can successfully handle the singular point occuring if the inertia term in the ion momentum balance equation is taken into account. Since not all data needed within this treatment for the simulation of realistic electronegative gases were available, a fictitious argon‐like gas has been considered which nevertheless can demonstrate the characteristic features of such a discharge. In particular, the influence of variations of the attachment and the ion‐ion recombination coefficients on the physical variables has b

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330204

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe radial model developed by Allen, Boyd, Reynolds and Chen [1, 2] for the ion collection of Langmuir probes is extended to describe the case of a non‐Maxwellian distribution of the electron energy. Assuming standard distributions, showing with respect to the Maxwell distribution an increasing deficite of fast electrons as the parameterkof the distribution increases, the electron‐retarded current characteristic, the potential distribution and the density profiles for electrons and ions in the probe sheath, ion‐current characteristics as well as graphs for the ion‐density determination are calculated for differentk. It is shown, that the application of the Chen model (k= 1) in plasma withk>1 leads only to a small error in the ion‐density me

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330205

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractWhen a spherical plasma pellet is irradiated symmetrically from all sides by high power laser beams, hot electrons are produced at the plasma resonance layer. They move in the inward radial direction causing a counter‐streaming cold electron current flowing outwardly to maintain the charge neutrality. In general, the interaction between the hot electrons and the counter‐streaming cold background electrons leads to broadening of the velocity distribution of the latter. For a given heat flux, the electron velocity distribution constrained by the requirements for not supporting beam plasma instabilities, predicts a minimum electron velocity in the plasma ablation zone. These considerations affect the efficiency of heat transfer from the hot corona to the cold core. The purpose of this paper is to study the dependence of core‐corona coupling on the electron velocity distribution, laser wavelength and other plasma parameters in d

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330206

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractLaser‐induced fluorescence on metastable and on resonant argon ion levels and spontaneous emission have been measured in two similar dc‐low pressure discharge configurations in dependence on gas pressure. Using a simple collision‐radiative model and various approximations a few results about pump rate ratios, electron temperatures, laser‐induced transition rates and relaxation rates from the metastable or resonant level are

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330207

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractThe hydrogen plasma and carbon ions flows generated at the target plates in the ITER tokamak scrape‐off layer are numerically investigated. A 2D model of hydrogen plasma and impurity ions is presented. The model is based on the electron‐ion Braginski fluid equations [1] for hydrogen plasma and rate equations for impurities. Arbitrary level of impurity ions concentration is assumed. Recycling of hydrogen, sputtering and self sputtering of carbon atoms at the target plates are taken into account. Equations of the model are solved in the slab geometry using 2D‐multifluid numerical code EPIT [2]. Problems of impurity ions retention and radiation in the divertor volume are analyzed. Results of calculations for ITER tokamak boundary plasma are presented, showing that poor retention is likely at high impurity concentration in the divertor volume. The radiation power can be a significant part of ingoing e

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330208

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

摘要:

AbstractA term is missing in the weak form of the total parallel momentum balance given in [1], and this affects the results of [2]. We present here the correct balance, and the corresponding results which supersede those given in [2]. The results of [3], on the contrary, are essentially unaffected.

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330209

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY

ISSN:0863-1042    

DOI:10.1002/ctpp.2150330201

出版商:WILEY‐VCH Verlag    

年代:1993

数据来源: WILEY