Effect of wave-particle interaction on the outflow of ions at high latitudes

The objective of the research is to use the low-frequency wave spectrum measured by the Plasma Wave Instrument on the DE-1 spacecraft to include the wave-particle interaction (WPI) in the different polar wind models that are available at Utah State University. A Monte Carlo technique was used to simulate the ion diffusion in the velocity space due to scattering by the waves. This enabled us to study the effect of WPI on the magnitude as well as the composition of the outflow of the ionospheric ions. In particular, in the first year the 1-D semi-kinetic code developed by Barakat and Schunk (1983) was modified in order to include the effect of the WPI

Radiation Rates for Low Z Impurities in Edge Plasmas

The role of impurity radiation in the reduction of heat loads on divertor plates in present experiments such as DIII-D, JET, JT-60, ASDEX, and Alcator C-Mod, and in planned experiments such as ITER and TPX places a new degree of importance on the accuracy of impurity radiation emission rates for electron temperatures below 250 eV for ITER and below 150 eV for present experiments. We have calculated the radiated power loss using a collisional radiative model for Be, B, C, Ne and Ar using a multiple configuration interaction model which includes density dependent effects, as well as a very detailed treatment of the energy levels and meta-stable levels. The "collisional radiative" effects are very important for Be at temperatures below 10 eV. The same effects are present for higher Z impurities, but not as strongly. For some of the lower Z elements, the new rates are about a factor of two lower than those from a widely used, simpler average-ion package (ADPAK) developed for high Z ions and for higher temperatures. Following the approach of Lengyel for the case where electron heat conduction is the dominant mechanism for heat transport along field lines, our analysis indicates that significant enhancements of the radiation losses above collisional radiative model rates due to such effects as rapid recycling and charge exchange recombination will be necessary for impurity radiation to reduce the peak heat loads on divertor plates for high heat flux experiments such as ITER.Comment: Preprint for the 11th PSI meeting, gzipped postscript with 11 figures, 14 page

Regional index of sustainable economic well-being development project: final report

This report presents results from a development project carried out by nef (the new economics foundation) on behalf of emda (the East Midlands Development Agency) and Natural England, to improve the methodologies used in the calculation of the R-ISEW (Regional Index of Sustainable Economic Well-Being)

Calculations of Energy Losses due to Atomic Processes in Tokamaks with Applications to the ITER Divertor

Reduction of the peak heat loads on the plasma facing components is essential for the success of the next generation of high fusion power tokamaks such as the International Thermonuclear Experimental Reactor (ITER) 1 . Many present concepts for accomplishing this involve the use of atomic processes to transfer the heat from the plasma to the main chamber and divertor chamber walls and much of the experimental and theoretical physics research in the fusion program is directed toward this issue. The results of these experiments and calculations are the result of a complex interplay of many processes. In order to identify the key features of these experiments and calculations and the relative role of the primary atomic processes, simple quasi-analytic models and the latest atomic physics rate coefficients and cross sections have been used to assess the relative roles of central radiation losses through bremsstrahlung, impurity radiation losses from the plasma edge, charge exchange and hydrogen radiation losses from the scrape-off layer and divertor plasma and impurity radiation losses from the divertor plasma. This anaysis indicates that bremsstrahlung from the plasma center and impurity radiation from the plasma edge and divertor plasma can each play a significant role in reducing the power to the divertor plates, and identifies many of the factors which determine the relative role of each process. For instance, for radiation losses in the divertor to be large enough to radiate the power in the divertor for high power experiments, a neutral fraction of 10-3 to 10-2 and an impurity recycling rate of netrecycle of ~ 10^16 s m^-3 will be required in the divertor.Comment: Preprint for the 1994 APSDPP meeting, uuencoded and gzipped postscript with 22 figures, 40 pages

On the Transport Equations for Anisotropic Plasmas

First, I attempt to present a unified approach to the study of transport phenomena in multicoponent anisotropic space plasmas. In the limit of small temperature anisotropies this system of generalized transport equations reduces to Grad\u27s 13-moment system of transport equations. In the collisionless limit, the generalized transport equations account for collisionless heat flow, cillisionless viscosity, and large temperature anisotropies. Also, I show that with the appropriate assumptions, the system of generalized transport equations reduces to all of the other major systems of transport equations for anisotropic plasmas that have been derived to date. Next, for application to aeronomy and space physics problems involving strongly magnetized plasma flows, I derive momentum and energy exchange collision terms for interpenetrating bi-Maxwellian gases. Collision terms are derived for Coulomb, Maxwell molecule, and constant collision cross section interaction potentials. The collision terms are valid for arbitrary flow velocity differences and temperature differences between the interacting gases as well as for arbitrary temperature anisotropies. The collision terms have to be evaluated numerically and the appropriate coefficients are presented in tables However, the collision terms are also fitted with simplified expressions, the accuracy of which depends on both the interaction potential and the temperature anisotropy. In addition, I derive the closed set of transport equations that are associated with the momentum and energy collision terms. Finally, I study the extent to which Maxwellian and bi-Maxwellian series expansions can describe plasma flows characterized by non-Maxwellian velocity distributions, with emphasis given to modeling the anisotropic character of the distribution function. The problem considered is the steady state flow of a weakly-ionized plasma subjected to homogeneous electric and magnetic fields, and different collision models are used. In the case of relaxation collision model, a closed form expression is found for the ion velocity distribution function, while for more regorous models (polarization and hard sphere) I have to use the Monte Carlo simulation. These provided a basis for determining the adequacy of a given series expansion. I find that, in general, the bi-Maxwellian-based expansions for the velocity distribution function is better suited to describing anisotropic plasmas than the Maxwellian-based expansions. (166 pages

An effective mass theorem for the bidimensional electron gas in a strong magnetic field

We study the limiting behavior of a singularly perturbed Schr\"odinger-Poisson system describing a 3-dimensional electron gas strongly confined in the vicinity of a plane $(x,y)$ and subject to a strong uniform magnetic field in the plane of the gas. The coupled effects of the confinement and of the magnetic field induce fast oscillations in time that need to be averaged out. We obtain at the limit a system of 2-dimensional Schr\"odinger equations in the plane $(x,y)$, coupled through an effective selfconsistent electrical potential. In the direction perpendicular to the magnetic field, the electron mass is modified by the field, as the result of an averaging of the cyclotron motion. The main tools of the analysis are the adaptation of the second order long-time averaging theory of ODEs to our PDEs context, and the use of a Sobolev scale adapted to the confinement operator

Anisotropic thermal magnetoresistance for an active control of radiative heat transfer

We predict a huge anisotropic thermal magnetoresistance (ATMR) in the near-field radiative heat transfer between magneto-optical particles when the direction of an external magnetic field is changed with respect to the heat current direction. We illustrate this effect with the case of two InSb spherical particles where we find that the ATMR amplitude can reach values of up to 800% for a magnetic field of 5 T, which is many orders of magnitude larger than its spintronic analogue in electronic devices. This thermomagnetic effect could find broad applications in the fields of ultrafast thermal management as well as magnetic and thermal remote sensing.Comment: 6 pages, 4 figure

Solving Modal Equations of Motion with Initial Conditions Using MSC/NASTRAN DMAP

By utilizing MSC/NASTRAN DMAP (Direct Matrix Abstraction Program) in an existing NASA Lewis Research Center coupled loads methodology, solving modal equations of motion with initial conditions is possible using either coupled (Newmark-Beta) or uncoupled (exact mode superposition) integration available within module TRD1. Both the coupled and newly developed exact mode superposition methods have been used to perform transient analyses of various space systems. However, experience has shown that in most cases, significant time savings are realized when the equations of motion are integrated using the uncoupled solver instead of the coupled solver. Through the results of a real-world engineering analysis, advantages of using the exact mode superposition methodology are illustrated