Plasmas with High Energy Particles and Relevant Magnetic Reconnection Processes*

Plasma macroscopic modes producing magnetic reconnection with finite frequencies of oscillation that have a phase velocity in the direction of the ion diamagnetic velocity have been identified in collisionless plasmas with strong neutral beam heating produced by the DIII-D and the JET machines. Modes with this feature had been proposed$^1$ to account for the observation of ``high-$\mathit m$ fishbones'' in plasmas with high energy particle populations$^2$, as they can resonate with the magnetic curvature drift frequencies of these populations. The theoretical model$^1$ introduced for the relevant reconnection layer was based on the presence of a ``finite inductivity'' prevailing over the effects of finite electrical resistivity$^3$. In view of a more recent theory$^4$, the excitation of electron temperature gradient driven modes producing strings of microscopic islands can be considered as a natural candidate to justify the envisioned finite inductivity through the coupling of these microreconnecting modes to the macroscopic modes. *Sponsored in part by ENEA of Italy and in part by the U.S. D.O.E. $^1$B. Coppi, Bull. Am. Phys. Soc. $\bf{45}$, 366 (2000). $^2$K. Toi, $\it et. al.,$ IAEA Fusion Energy 1998, F1-CN69-EXP1/19. $^3$B. Coppi, $\it{Phys. Fluids}$ $\bf{8}$, 2273 (1965). $^4$B. Coppi, in ``Collective Phenomena in Macroscopic Systems'' pg. 59, Eds. G. Bertin $\it{et.al.,}$ Publ. World Scientific (2007).