[en] The two dimensional eigenvalue equation describing the dissipative trapped electron mode is solved exactly in the limit of the mode overlapping many rational surfaces using the Pogutse model for the magnetic field and the pitch angle collision operator. The trapped electron contribution to the growth rate decreases, with respect to the standard theory, by a factor of order Δ/chi sub(T) << 1 where chi sub(T) is the position of the turning point and Δ the distance between rational surfaces

[en] When the resonance condition of the particle-wave interaction is varied adiabatically, the particles trapped in a wave are found to form phase space holes or clumps that enhance the particle-wave energy exchange. This mechanism can cause increased saturation levels of instabilities and even allow the free energy associated with instability to be tapped in a system in which background dissipation suppresses linear instability

[en] A theoretical model for investigating the effect of the trapped energetic particles (EPs) on the resistive wall mode (RWM) instability is proposed. The results demonstrate that the trapped EPs have a dramatic stabilizing effect on the RWM because of resonant interaction between the mode and the magnetic precession drift motion of the trapped EPs. The results also show that the effect of the trapped EPs depends on the wall position. In addition, the stabilizing effect becomes stronger when the plasma rotation is taken into account. For sufficiently fast plasma rotation, the trapped EPs can lead to the complete stabilization of the RWM. Furthermore, the trapped EPs can induce a finite real frequency of the RWM in the absence of plasma rotation.

[en] The need for theoretical previsions concerning anomalous transport in large Tokamaks, as well as the recent results of PLT, ask the question of the process responsible for non-linear saturation of trapped-ion instabilities. This in turn necessitates the knowledge of the linear behaviour of these waves at large frequencies and large radial wavenumbers. We study the linear dispersion relation of these modes, in the radially local approximation, but including a term due to a new physical effect, combining finite banana-width and bounce resonances. Limiting ourselves presently to the first harmonic expansion of the bounce motion of trapped ions, we show that the effect of finite banana-width on the usual trapped-ion mode is complex and quite different from what is generally expected. In addition we show, analytically and numerically, the appearance of a nex branch of this instability. Essentially due to this new effect, it involves large frequencies (ω approximately ωsub(b) and is destabilized by large radial wavelengths (ksub(x) Λ approximately 1, where Λ is the typical banana-width). We discuss the nature of this new mode and its potential relevance of the experiments

No abstract available

[en] The Doublet III experiment has as its primary goal the test of confinement of noncircular cross section toroidal plasmas in the regime where trapped ion effects may be operative. The importance of the experiment stems from the potential of noncircular cross section toroidal plasmas for fusion reactors, which will operate in a regime that may be dominated by trapped ion effects. The guiding principles for the design of the Doublet III device have been: (1) to minimize the physics risks in reaching the desired regime, i.e., to use the smallest possible extrapolations from existing experimental results, (2) to minimize technological risks, i.e., to use proven technology whenever possible, and (3) to minimize costs and time involved in achieving the goal

[en] Separate abstracts were prepared for each of the two included sections

[en] A study of the trapped ion instability in the real geometry of the large Tokamaks leads to the consideration of a new branch of that instability, driven by a resonance with the magnetic drift of the particles, both in collisional and non collisional regimes

[en] The new design for the Boeing High Average Power Free Electron Laser will operate at 1KW average power (0.63 μm) with a peak current of 132A. Simulations are used to investigate the trapped-particle instability and diffraction effects. Incorporating large desynchronism may prove to be a useful method of controlling the trapped-particle instability

[en] It is shown that in steady state the dissipative trapped electron mode does not give rise to net plasma heating. However, it does cause anomalous energy exchange between electrons and ions, with the ions heating and the electrons cooling