摘要:

We present a diffusion model describing electron transport in plasma thrusters. The model is obtained by a diffusion approximation technique from a kinetic transport model including scattering at the walls. Realistic attachment and secondary emission processes are taken into account. Numerical solutions of the model are compared with Monte Carlo simulations and a fairly good agreement is observed at a much lower CPU-cost.

ISSN:0041-1450    

DOI:10.1080/00411459808205621

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We consider a nonlinear Boltzmann-like model of the interaction between algae and photons. Existence, uniqueness and positivity of the solution are proved by using the theory of nonlinear semigroups generated by affine operators in order to take into account nonhomogeneous boundary conditions that specify the radiation entering through the boundary surface.

ISSN:0041-1450    

DOI:10.1080/00411459808205622

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this paper we analyse some spectral properties of time dependent linear Boltzmann equation with external field in both spatially homogeneous and inhomogeneous cases. Under certain conditions on the field we recover the classical Voigt result that the essential spectrum of the full Boltzmann semigroup coincides with that of the transport semigroup. We also discuss an application of this result to the asymptotic analysis of Boltzmann equation.

ISSN:0041-1450    

DOI:10.1080/00411459808205623

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

We survey the problem of finding steady solutions for the Boltzmann equation. Then we present a proof that the Boltzmann equation in a slab, with boundary conditions of diffuse reflection and mass conservation at the wall and assigned total mass (per unit area) in a slab has at least one positive solution. The physical model is provided by Maxwellian molecules with angular cutoff. The equation is rewritten after a change of variables which is shown to be invertible.

ISSN:0041-1450    

DOI:10.1080/00411459808205624

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In the frame of extended kinetic theory, a kinetic model is proposed, which allows for elastic and inelastic scattering. The gas atoms have an internal structure, namely an arbitrary finite number of internal energy levels. Transitions between different energy levels may occur by absorption or emission of photons of the self-consistent radiation field as well. The main properties of the global collision operator are investigated, equilibria are determined, and an H theorem is proved. The transport problem of a swarm of single level test particles diffusing in a background of multilevel field particles is then discussed along the same lines.

ISSN:0041-1450    

DOI:10.1080/00411459808205625

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Radiative transfer through a cloud with stochastic clumps is studied into an abstract Banach space setting. By using a generalized Fourier expansion, a sequence of evolution equations is deduced, which approximates the exact evolution equation for the expectation.

ISSN:0041-1450    

DOI:10.1080/00411459808205626

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

General principles of Monte Carlo(MC) methods for integral equations and their application in particle transport are considered. In contrast to weight optimization of MC methods, here the distribution of trajectories is assumed to be given and fixed and estimators are varied. Some efficient and original non-simulation estimators are described. In these estimators approximations of the solution to the adjoint problem are used.

ISSN:0041-1450    

DOI:10.1080/00411459808205627

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The initial boundary value problem for the one-dimensional Broadwell model in a slab with reflection and with a given time dependent source term on the boundary is considered.

ISSN:0041-1450    

DOI:10.1080/00411459808205628

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The analysis of runaway phenomena with the use of the Boltzmann equation shows that the time evolution of the distribution function and of the other quantities of interest, for example the average velocity, occurs on two time scales: the short time scale of the collisional equilibrium and the long time scale of the runaway flux. Under suitable conditions on the collision kernels, these two time scales are well separated. In this paper, we present some analytical results for the BGK model based on a multiple time scale expansion: in particular, we derive approximate analytical expressions for the distribution function, the average velocity and the collision number and compare them with the numerical solution.

ISSN:0041-1450    

DOI:10.1080/00411459808205629

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Procedures are discussed for calculating the steady-state current for linear quantum transport problems subject to inflow boundary conditions. A review of classical kinetic models is given, and techniques (based on quantum BGK modes) for solving the stationary Wigner equation with inflow BC's are discussed. Lastly, uniqueness of the steady-state current is shown.

ISSN:0041-1450    

DOI:10.1080/00411459808205630

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor