Altair Souza de Assis

Discrete Alfvén waves in solar loop prominences

It is shown that a discrete Alfvén wave can explain the natural oscillations of solar loop prominences by considering the existence of a current flow. Discrete Alfvén waves are a new class of Alfvén waves which is described by the inclusion of the finite ion cyclotron frequency (ω/ωcl≠0) and/or the equilibrium plasma current. In this paper we consider only the effect of the current since in solar prominences (ω/ωcl≈0). We have modeled the solar prominences as a cylindrical plasma, surrounded by vacuum (corona), with L ≫ a where L and a are the plasma column, length, and radius, respectively. We have calculated the spectrum of the discrete Alfvén waves as function of the magnitude and shape of the plasma current.

Magnetosonic and kinetic Alfvén current drive analysis

Quasilinear equations are used together with the energy conservation equation to assess the merits of magnetosonic and kinetic Alfven current drive. It is found that the Alfven mode has a higher gain in terms of efficiency and current than the magnetosonic mode.

Coronal Loop Heating by the Fast Surface Wave

Although coronal plasmas are considered to be collisional, it is well known that particle collisions do not provide effective energy dissipation. It is shown that the wave-particle resonant interactions can dissipate energy fast enough to sustain the coronal temperature.

Wave-Particle-Electric Field Synergetic Auroral Electron Acceleration

We discuss afresh the problem of the auroral electron acceleration based on the controversy reports of Bryant, D. A. et al.: 1992, Phys. Rev. Lett. 68, 37, and Borovsky, J.: 1992, Phys. Rev. Lett. 69, 1054, related to which mechanism is more tenable to accelerate auroral electrons: dc electric field generated somehow in aurora or wave-particle interaction due to auroral wave turbulence? Here, we show that both mechanisms are important, and what is most likely to happen in aurora is that the turbulence and the dc electric field structure will assist each other so as to synergetically accelerate those electrons.