Closed drift thrusters are reviewed. The publications on these thrusters constitute a large body of information. This article can therefore include only the most prominent theoretical and experimental features of closed drift thrusters. In some regards, this article is also an attempted synthesis of the differing views of these thrusters found in literature, as well as in our own work.In a closed drift thruster, the electric field that accelerates the ions is established by an electron current that passes through and is impeded by a magnetic field. The precessing electrons in this magnetic field follow a closed drift path giving this thruster its name. Closed drift thrusters are divided into magnetic layer and anode layer types, based both on the geometrical and material differences in the discharge channels of the two types, and on the different physical processes that take place within the discharge plasma.Considered as a whole, the publications on closed drift thrusters constitute an impressive body of information that, for the most part, was generated in Russia independently of US research on electric thrusters.

The end-Hall ion source has been developed for high-current, low-energy ion-beam applications. Beam currents up to 1 A have been obtained at mean ion energies of 30–120 eV, using Ar, Kr, or O2. The end-Hall source should be useful in applications where large currents of low-energy ions are used in conjunction with thin-film deposition to increase adhesion, modify stress, increase density or hardness, produce a preferred orientation, or improve step coverage. It should also be useful for reactive etching. It is suited for use in a production environment because it is simple, mechanically rugged, and reliable.

By adopting Nester's 4−dimensional special orthonormal frames, the tetrad equations for vacuum gravity are put into explicitly causal and symmetric hyperbolic form, independent of any time slicing or other gauge or coordinate specialization.

Lovelock actions(more precisely, extended Gauss-Bonnet forms) when variedas Cartan forms on subspacesof higherdimensionalflatRiemannian manifolds,generatewellset,causalexterior differential systems. In particular,the Einstein-Hilbert action4-form, variedon a 4 dimensionalsubspace of El0, yieldsa wellsetgeneralized theory of gravityhaving no constraints.Iticci-flat solutionsareselected by initial conditionson a bounding 3-space.

Calculations have been made of cross sections for energy and momentum transfer in binary collisions between like pairs of Ar, Kr, and Xe atoms in the energy range from about 1 to 1000 eV. These calculations were made using a classical model with pair interaction potentials for the rare gases developed from experimental sources, e.g., investigations of specific heats, viscosities, solid-state parameters, and scattering data. Cross sections in this energy range have not been available. The cross sections exhibit a rapid decrease from accepted values at thermal energies as the interaction energy increases. This behavior can be used to understand directed beam propagation limits as well as particle propagation within a plasma. Experimental data have also been fit to a theoretical expression for the Ar resonance charge exchange cross section over the same energy range.