[en] Current understanding of electron cyclotron heating in the ELMO Bumpy Torus (EBT) is reviewed and the propagation characteristics of the different modes are described for EBT geometry. Wave absorption processes near the second harmonic resonance (where the annulus is observed to form in EBT) are discussed. Calculations of single particle energy gain are presented for finite wavelength waves propagating in a magnetic mirror geometry. It is shown that the heating is highly pitch angle-dependent and the relativistic effects are quite important even at moderate energies. Calculations are presented which suggest that coherent, wave-particle interactions may be important in producing the annulus from a population of particles having small initial perpendicular energies

[en] It is shown that the microwave power P/sub μ/ effectively vanishes near Ω/sub e/ (s) approx. = ω. The implication of this is that for fixed epsilon passing particles are preferentially heated and for fixed pitch angle high energy particles are preferentially heated. The effect of the heating is to increase v/sub perpendicular to/, pushing passing particles toward the trapped-passing boundary where confinement is poor

[en] The process of Budden tunnelling of obliquely propagating extraordinary mode is investigated in plasmas whose parameters vary along the magnetic field

[en] A simple model is presented for the production and absorption of ordinary and extraordinary mode energy in various regions of the ELMO Bumpy Torus plasma. The plasma is divided into two regions: (I) the low magnetic field side of the extraordinary mode cutoff and (II) the high field side of the cutoff. Energy balance equations are written for the sources (injection, mode conversion, and tunneling) and sinks (mode conversion, absorption, and tunneling) in each region, and simplified models are introduced to account for each of these processes. Since a typical ray makes several reflections from cavity wall surfaces before being absorbed, additional simplifying assumptions are made that the wave fields are an isotropic incoherent superposition of plane waves and that the energy density of each mode is uniform in a given region

[en] The equilibrium and nonlocal stability properties of collisionless, high-β, theta-pinch plasmas are investigated using a Vlasov description and using a two-fluid description. The equilibrium configuration is assumed to be an infinitely long, azimuthally symmetric plasma column with currents purely in the azimuthal direction and magnetic field purely in the axial direction. For the stability analysis, primary emphasis is on the frequency regime OMEGA/sub i/less than parallel bar ω parallel bar less than OMEGA/sub e/. The general procedure for constructing high-β theta-pinch equilibria within the framework of the steady-state Vlasov-Maxwell equations is discussed. Properties are calculated for a number of sharp-boundary and diffuse-boundary, rigid-rotor Vlasov equilibria and general equilibrium relations that pertain to the entire class of rigid-rotor equilibria are presented. A method is presented for reconstructing the distribution function of a rigid-rotor equilibrium if the temperature, rotational frequency, and either the density or magnetic field profile is known. Equilibrium properties of theta-pinch plasmas are also investigated using a two-fluid description and a comparison is made between the two-fluid and ideal MHD formulations. A two-fluid model is developed to describe the linear electrostatic stability of cylindrically symmetric plasmas with axial magnetic fields

[en] The basic strategy of the theoretical study of microwave heating in the ELMO Bumpy Torus (EBT) is outlined and the current status of the various aspects of the study is described. There are four broad areas which are being investigated: (1) heating and wave damping mechanisms, (2) the geometrical optics of microwave propagation in EBT, (3) reflection and mode conversion effects at regions such as cutoff and resonances where the geometrical optics approximation breaks down, and (4) nonlinear effects such as ponderamotive effects and parametric decay. Details are given of the geometrical optics code which has been developed to do ray tracing in arbitrary three dimensional (3-D) plasma equilibria. Examples are given for plasma parameters characteristic of EBT-I and EBT-II. Details are also given of the stochastic heating model currently in use with the 1-D transport code and of the linear wave damping model used in the ray tracing code. The most pressing problems of physics yet to be addressed and the directions for future work are indicated

[en] The heating of the Advanced Toroidal Facility now under construction at Oak Ridge National Laboratory has been investigated using ray tracing techniques. The effect of electron cyclotron waves at the second harmonic resonance is studied using the RAYS geometrical optics code assuming anticipated steady state parameters. A comparison is made of the heating efficiency using two launching schemes: a linearly polarized antenna providing a narrow beam and a T E₀₂ waveguide. The first pass ray tracing calculations are incorporated in a wall reflection/power balance model which includes the effects of wall reflected rays and wall losses. It is shown that the power absorbed in the plasma after multiple reflections is preferentially absorbed near the center of the plasma. A significant fraction of the incident power is predicted to ultimately be deposited in the plasma, rather than lost to walls and ports

[en] The theory, structure, and operation of the code are described. Mathematical details of equilibrium subroutiones for slab, bumpy torus, and tokamak plasma geometry are presented. Wave dispersion and absorption subroutines are presented for frequencies ranging from ion cyclotron frequency to electron cyclotron frequency. Graphics postprocessors for RAYS output data are also described

[en] The ray tracing code, RAYS, requires a subroutine module which supplies magnetic field and density as well as their gradients, to propagate rays using the cold plasma approximation. In order for the ray trajectory to remain a solution of the dispersion relation, D(ω,anti κ,anti r) = O, the spatial derivatives of anti β and n/sub e/ numerically defined by the module must be a good approximation to the analytic derivatives of the field quantities themselves. This consistency, coupled with initializing the ray on a root of the dispersion relation, D(ω,κ₀,anti r₀) = O, is sufficient for the ray to satisfy the dispersion relation along the ray. An additional requirement is that n/sub e/ be constant on a magnetic field line. Although this is not a necessary condition for the ray to satisfy the dispersion relation, the physics of the problem may dictate that this constraint be satisfied. The example of lower hybrid (LH) heating is described where this requirement should be satisfied in order to get meaningful results. A computationally efficient and robust way to solve these problems is to use 3-D cubic spline interpolation of a data set with the desired model for anti β and the accurate calculation of toroidal flux, PSI. The advantages and use of splines are the subject of this paper. 2 refs., 5 figs

[en] A mechanism for heating and driving currents in very overdense plasmas is considered based on a double-mode conversion: Ordinary mode to Extraordinary mode to electron Bernstein wave. The possibility of using this mechanism for plasma buildup and current ramp in the National Spherical Torus Experiment is investigated