Roles of Fast-Cyclotron and Alfven-Cyclotron Waves for the Multi-Ion Solar Wind

Using linear Vlasov theory of plasma waves and quasi-linear theory of resonant wave-particle interaction, the dispersion relations and the electromagnetic field fluctuations of fast and Alfven waves are studied for a low-beta multi-ion plasma in the inner corona. Their probable roles in heating and accelerating the solar wind via Landau and cyclotron resonances are quantified. We assume that (1) low-frequency Alfven and fast waves have the same spectral shape and the same amplitude of power spectral density; (2) these waves eventually reach ion cyclotron frequencies due to a turbulence cascade; (3) kinetic wave-particle interaction powers the solar wind. The existence of alpha particles in a dominant proton/electron plasma can trigger linear mode conversion between oblique fast-whistler and hybrid alpha-proton cyclotron waves. The fast-cyclotron waves undergo both alpha and proton cyclotron resonances. The alpha cyclotron resonance in fast-cyclotron waves is much stronger than that in Alfven-cyclotron waves. For alpha cyclotron resonance, an oblique fast-cyclotron wave has a larger left-handed electric field fluctuation, a smaller wave number, a larger local wave amplitude, and a greater energization capability than a corresponding Alfven-cyclotron wave at the same wave propagation angle \theta, particularly at $80^\circ$ < \theta < $90^\circ$. When Alfven-cyclotron or fast-cyclotron waves are present, alpha particles are the chief energy recipient. The transition of preferential energization from alpha particles to protons may be self-modulated by differential speed and temperature anisotropy of alpha particles via the self-consistently evolving wave-particle interaction. Therefore, fast-cyclotron waves as a result of linear mode coupling is a potentially important mechanism for preferential energization of minor ions in the main acceleration region of the solar wind.Comment: 29 pages, 10 figures, 3 tables. Accepted for publication in Solar Physic

Community radio in the West: a legacy of struggle for survival in a state and capitalist controlled media environment

In this article the legacy of struggle by community radio in the West is analysed from a comparative perspective. More specifically, the focus of this article is on Western media policies towards community radio. It is argued that while many community radio discourses, theories and policies are oriented towards developing countries and emerging democracies, community radio stations in the West are often forced to operate in the margins. Case studies on the US, the UK and Belgium are presented. Some influence of distinct regulatory paradigms can be observed, but overall in each of these countries community radio stations have a legacy of struggle for their existence and survival. This exposes the need to account for the distinct nature of community radio in (Western) regulatory regimes. A common thread in the cases being presented is the difficulty involved in (local) community radio legitimating its existence on the FM-band alongside commercial and public broadcasters. Unlike these, community radio movements have little lobbying power and are usually positioned as rogue and unprofessional actors within the broadcasting community. From a democratic perspective emphasizing the importance of participation and civic culture, Western media policies urgently need to create an enabling environment for participatory community radio initiatives