摘要:

AbstractSingle‐ and two‐particle states in dense plasmas differ significantly from those of ideal systems and have especially a finite lifetime. Both the bound states and the continuum edges of two‐particle states are controlled by “complex single‐particle energies”. Furthermore, the thermodynamics can be given by these quantities. For this reason we study the spectral weight function of the single‐particle Green's function and solve the equivalent dispersion relation self‐consistently in the Montroll‐Ward approximation of the self energy. We give results for the continuum edges of a hydrogen plasma and of a model electron‐hole plasma and discuss approximations for th

ISSN:0863-1042    

DOI:10.1002/ctpp.2150350602

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe nonlinear three‐wave interactions of the surface waves (SW) which exist at the plasma‐like medium‐metal interface are considered. The studied SW are caused by collective phenomena in the plasma‐like medium and propagate across an external magnetic field which is parallel to the interface. The wave coupling coefficients are obtained in the most general form and are expressed through the second order nonlinear susceptibilities. The simple case when the plasma‐like medium allows a hydrodynamical description is considered as well. The conditions providing the most effective interaction between the waves are discussed and the analytical expressions describing the amplitude evolution of the SW under such interaction are given. The possibility of realization of a parametric generator based on the SW nonlinear interaction is discussed. The characteristic length of the nonlinear medium providing the effective interaction is estimated for several import

ISSN:0863-1042    

DOI:10.1002/ctpp.2150350603

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe concentration of metastable atoms can significantly be influenced by changing the gas temperature [1]. Starting from a set of balance equations, consisting of the balance equation for the electrons, the balance equation for excited atoms and the current balance equation the impedance behaviour is calculated in dependence on the gas temperature. Based on a theoretical description of the discharge plasma a nonlinear equivalent circuit representing the behaviour of the positive column at higher gas‐temperatures (250 K – 500 K) is developed. The circuit posseses only positive parameters for the reactances which can be calculated by means of the elementary processes occuring in the discharge plasma. Experimental investigations of the static current/voltage characteristic and the impedance behaviour support the proposed circuit mo

ISSN:0863-1042    

DOI:10.1002/ctpp.2150350604

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractExperimental study of the electron and ion density determined by Langmuir probe is presented. The probe data have been obtained on FALP apparatus for electron (and ion) number densities ranging from 1012m−3to 1016m−3, at electron temperatures equal to room temperature and also roughly ten times higher and at neutral pressures from 60 Pa to 150 Pa.The number densities of electrons for all measured probe data have been deduced from the electron current to the probe at the space potential and also by means of OML method from the electron current measured for positive probe with respect to the space potential. In the paper it is shown that in the flowing afterglow plasma the values of the electron density determined according both methods are in a good agreement and it is possible to take them as the reference number density for comparison with apparent ion densities obtained from the ion current.The number densities obtained from the ion currents in the ion accelerating region (negative probe with respect to the space potential) according to different applicable probe theories have been compared with reference value. It is found that the best agreement between the number densities evaluated from the electron current and from the ion current gives the theory of ion collection by Tichý et al. [16], which takes into account the collisions of ions with neutrals in the space charge sheath around the probe provided that the conditions correspond to the OML re

ISSN:0863-1042    

DOI:10.1002/ctpp.2150350605

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractThe positive column of low pressure DC glow discharges in Xe/Cl2and Kr/Cl2gas mixtures has been investigated with respect to its UV radiation power and radiative efficiency for a wide range of parameters (total gas pressure: 1–30 mbar, current 10–30 mA, partial pressure of Cl2: 1–33%). Also the radial distribution of the particle number densities of XeCl* (B) and KrCl* (B) has been determined by absolutely calibrated emission spectroscopy. Optimum UV (190–350 nm) output and efficiency has been found in gas mixtures with a relative Cl2partial pressure of 2–3% and total gas pressure of 12–18 mbar. At these parameters, the UV radiation power per column length is greater than 40 Watt/m with a radiative efficiency of 15–18%. These discharges could be used for UV induced photochemi

ISSN:0863-1042    

DOI:10.1002/ctpp.2150350606

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractInterferometric measurements of radial gas density distributions have been performed on the cylindrical positive column of DC low pressure glow discharges (LPGD) in pure Xe and Xe/Cl2gas mixtures. Absolute gas temperatures have been measured by thermocouples. In the mixtures, the gas temperature is several hundred Kelvin above the temperature in pure Xe. Additionally, the radial distribution of the gas density in the mixtures cannot be described by Bessel profiles, which would result from Schottky's diffusion theory. Combined with field strength measurements, radial profiles ofE/N(electric field strength/neutral density) have been determined. Results of this work will be useful for model developments of LPGD in rare‐gas/Cl2mixtures but also for the general understanding of the positive column in attaching gase

ISSN:0863-1042    

DOI:10.1002/ctpp.2150350607

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

摘要:

AbstractIf a permanent magnet has both a homogeneous polarization inside the material and a linear demagnetization characteristic in external fields, its magnetic field can be expressed using a surface pole model. For magnets satisfying these conditions and, in addition, having a rectangular shape, the fields at any given point in space can be calculated analytically. An algorithm for this calculation is presented in a form that can easily be implemented into a computer program. In our experiments we used Nd2Fe14B magnets to support low pressure glow discharges by magnetic fields. The magnets can be seen as composed of elementary magnets with rectangular shape, for which the magnetic field distribution is calculable. We present results of field calculations for various configurations of permanent magnets that we used in hollow cathode and Penning discharges.

ISSN:0863-1042    

DOI:10.1002/ctpp.2150350608

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY

ISSN:0863-1042    

DOI:10.1002/ctpp.2150350601

出版商:WILEY‐VCH Verlag    

年代:1995

数据来源: WILEY