摘要:

AbstractCylindrical plasma equilibria forming self‐consistent structures of electric currents and magnetic fields, caused by a homogeneous electric field, are treated with single particle theory and resistive MHD (fluid) theory. Three steps of increasing complexity and closer approach towards reality have been discussed:1The “ideal” (strictly force‐free) structure, with the current density parallel to the magnetic field everywhere.2The incorporation of currents normal to the field into the structure.3The incorporation of the plasma inhomogeneity, i.e. of the (radial) density profile into the current‐field plasma structure.A possible fourth step is indicated. Several remarkable properties of these structures are discussed by numerical integration or (in limiting cases) by analytical integration of the equations describing the field and the current distribution. For instance, simple results are obtained in the first step: In a force‐free structure this relation between currentJz, central current densityj0and axial field strengthH0is valid:Jzjo/H 02≈ 8.2174. And the typical radial extension of the structureγis given byγjo/H0≈ 1.47 or ≈ 1.62 (depending on the definition ofγ). These results can be improved if deviations between current and field directions are taken into account. In case of the third step, some basic relations only are given without calculating quantitative results.Approximately, such model structures may be applicable to magnetically confined plasmas with internal currents as used in

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380502

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractModal and focusing properties of the plasma based waveguide having a parabolic profile of the electron density are treated for x‐ray beams with the ray‐transfer and paraxial‐envelope equations. Conditions on the single mode, multimode and leaky mode propagation in straight and tapered plasma channels are evaluated. The near‐ and far‐field patterns of these modes are calculated. The main result is that the mode structure is guide length and wavelength dependent, resulting in the guide length and wavelength dependent conditions for the guiding and focusing. The modal analysis finds its application in the field of x‐ray lasers, extremly high harmonic generation and x‐ray beam focusing, in which it may be helpful to design guides for optimum beam propagation. Futhermore, the mode properties are extremly simple and provide an idealised model for the real plas

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380503

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractIn sequel to earlier observations on soliton dynamics in the plasmas, a few more features on solitons and double layers have been studied in a nonisothermal plasma conceiving multi‐temperature electrons. The basic equations governing the plasma dynamics, based on quasipotential analysis, are first reduced to an energy integral equation known as Sagdeev potential equation, to elucidates the salient features plasma of acoustic modes associating to those furthered in laboratory and space plasmas. The Sagdeev potential equation, under small amplitude approximation derives various kinds of Korteweg de Vries (K‐dV) equations in nonisothermal plasma and is solved by employing a modified approach of simple wave solution technique called as tanh‐method. The analyses show, under certain conditions, the remarkable properties of soliton propagation and double layers of compressive and rarefactive nature in the plasmas. The outcome of the observations could be of interest further in understanding the features of various plasma acoustic waves in laboratory and space pl

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380504

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractStarting with the expression for the permittivity tensor for a loss‐free magnetoplasma the low‐frequency limits of its eigenvalues are calculated. They are used for the dispersion relations and polarization ratios of the shear Alfvén mode and the fast magnetosonic

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380505

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractResults of numerical evaluation of equilibrium compositions and mobilities in plasmas formed in the mixtures of argon and chlorine are given. The temperature dependence of the number densities of the components and their mobilities in function of temperature for low‐pressure (from0, 1kPato 1,0kPa) and low‐temperature (from 500Kto 5 000K) argon plasmas with 20% and 30% of added chlorine are evaluated. It is assumed that the system is kept under constant pressure and that a corresponding state of local themodynamical equilibrium is attained in it. A previously derived expression for the modified Debye radius, offering the possibility to treat the plasmas considered as weakly non‐ideal in the whole temperature range, is used and the cut‐off at the Landau length rather than of the smallest of ionic radii is introduced. This alteration in the evaluatin procedure brings different change in the final numerical results for all the relevant quantities.It is found that the equilibrium plasma composition depends considerably on the presence of chlorine in the whole temperature range for both pressures; the addition of chlorine significantly enhances number densities of all relevant charged constituents. This fact influences of the electron and ion collision frequencies and their mobilit

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380506

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractIn plasmas with helium‐like bound states electrostatic screening inside the atom gives rise to deviations from the Debye‐Hückel chemical potential. Assuming a variational solution for the ground state of the helium‐like atom the corresponding Free Energy is explicitely given. The result provides a simple means to describe the forming of bound states in consistency with the surrounding plasma and surpasses in this sense perturbation th

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380507

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractPublished data on the impact ionization of rarefied gases by electrons are analysed where from a simple explanation of the Langmuir paradox follows. This approach gives likewise an opportunity to explain some other anomalous phenomena observed when ionizing gas atoms or molecules by an electron impact.

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380508

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractThe two‐point correlation function is reduced to expansion in terms of the two‐time correlation function with improved accuracy. The ideas reported extends the applicability area for calculations typical to the weak plasma turbulence theory on the “strong plasma turbulence”. Some implications of the results obtained for the dynamics of Langmuir turbulence are di

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380509

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

摘要:

AbstractSpectroscopic data indicate that fully ionised carbon ions occur in capillary discharge experiment using a polyethylene tube. On the basis of the simultaneously obtained data for electron density and temperature we calculate the charge‐state distribution. The theoretical model takes into account several dense plasma effects and yields the detailed composition of the polyethylene plasma over time. For typical densities of the discharge plasma a temperature of ≥ 30eV/kBis shown to be sufficient to generate a substantial amount of fully ionised car

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380510

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY

ISSN:0863-1042    

DOI:10.1002/ctpp.2150380501

出版商:WILEY‐VCH Verlag    

年代:1998

数据来源: WILEY