Mode-coupling and nonlinear Landau damping effects in auroral Farley-Buneman turbulence

The fundamental problem of Farley-Buneman turbulence in the auroral $E$-region has been discussed and debated extensively in the past two decades. In the present paper we intend to clarify the different steps that the auroral $E$-region plasma has to undergo before reaching a steady state. The mode-coupling calculation, for Farley-Buneman turbulence, is developed in order to place it in perspective and to estimate its magnitude relative to the anomalous effects which arise through the nonlinear wave-particle interaction. This nonlinear effect, known as nonlinear ``Landau damping'' is due to the coupling of waves which produces other waves which in turn lose energy to the bulk of the particles by Landau damping. This leads to a decay of the wave energy and consequently a heating of the plasma. An equation governing the evolution of the field spectrum is derived and a physical interpration for each of its terms is provided

Injection, compression and stability of intense ion-rings

Recent advances in pulsed high power ion beam technology make possible the creation of intense ion-rings with strong self-magnetic fields by single pulse injection. Such ion rings have several uses in controlled fusion e.g., to produce a min parallel B parallel magnetic geometry with a mirror ratio much higher than is possible with external conductors. For even stronger ion rings a min parallel B parallel with closed lines of force (ASTRON type) can be created. For this purpose, since the ion energies required are much higher than are available from high power sources, magnetic compression can be utilized to increase the ion energy. The success of this scheme depends critically on the stability of the ion ring. The low frequency perturbations of the ring-plasma system is examined by means of a generalization of the energy principle which established sufficient conditions for stability. The high-frequency micro- instabilities and their nonlinear consequences are discussed in terms of conventional techniques. (auth

Mode-conversion induced tearing effects in a plasma neutral sheet

A new collisionless dissipation mechanism which can drive tearing modes in a plasma neutral sheet is described. The new mechanism relies on the presence of a background cold plasma which leads to mode conversion into a continuous spectrum of cold plasma waves

Evolution and Statistics of Current Sheets in Coronal Magnetic Loops

A resistive magnetohydrodynamic model is proposed for a straightened coronal loop subject to continuous slow fluctuating random footpoint driving. The characteristic time scale of this driving motion is much longer than the Alfv'en transit time along the loop. The governing equations for this model are integrated numerically until a statistical steady state is attained. In steady state the spatial structure of the magnetic field is dominated by thin regions of intense current density indicative of current sheets. Using a simple model of resistive reconnection the statistical steady state can be understood as a random superposition of current sheets. This model predicts the scaling of the sheet parameters and the global heating with resistivity. The scaling is verified over the small range of values achievable in these numerical experiments

High power electron and ion beam research and technology

Topics covered in volume II include: collective accelerators; microwaves and unneutralized E-beams; technology of high-current E-beam accelerators and laser applications of charged-particle beams. Abstracts of twenty-nine papers from the conference were prepared for the data base in addition to six which appeared previously. (GHT