Dwarf (or dark) molecular clouds and molecular clumps have a lifetime which is greater than their dynamical time and must therefore be, in an average sense, in mechanical equilibrium. Equilibrium perpendicular to a global magnetic field is by magnetic forces and it is proposed that along the field the gas is supported by an Alfvén wave pressure force. A selfconsistent analytical model, utilisin...

Turbulence of magnetohydrodynamic waves in nature and in the laboratory is generally cross-helical or nonbalanced, in that the energies of Alfvén waves moving in opposite directions along the guide magnetic field are unequal. Based on high-resolution numerical simulations it is proposed that such turbulence spontaneously generates a condensate of the residual energy E(v) - E(b) at small field-p...

A quantitative analysis is presented of the FAST satellite electric field and particle flux data during an EISCAT heating experiment run on 8 October 1998. Radio frequency heating, modulated at 3 Hz, launched ULF waves from the ionosphere into the lower magnetosphere. The ULF waves were observed in FAST data and constituted the first satellite detection of artificially excited Alfvénic ULF wave...

Context. Using Particle-In-Cell simulations i.e. in the kinetic plasma description, the discovery of a new mechanism of parallel electric field generation was recently reported. Aims. We show that the electric field generation parallel to the uniform unperturbed magnetic field can be obtained in a much simpler framework using the ideal magnetohydrodynamics (MHD) description. Methods. We solve n...

The Magnetospheric Multiscale mission is employed to examine intense Poynting flux directed along the background magnetic field toward Earth, which reaches amplitudes of nearly 2 mW/m2. The event is located within the plasma sheet but likely near the boundary at a geocentric distance of 9 RE in association with bulk flow signatures. The fluctuations have wavelengths perpendicular to the magneti...

Examples of one plasma expanding into another and the consequent radiation of wave energy are abundant in both nature and the laboratory. This work is an experimental study of the expansion of a dense laser-produced plasma ~initially, nlpp /n0@1) into a magnetized background plasma (n0 52310 cm) capable of supporting Alfvén waves. The experiments are carried out on the upgraded Large Plasma Dev...

Proton acceleration at a parallel coronal shock is modeled with self-consistent Alfvén wave excitation and shock transmission. 18 50 keV seed protons at 0.1% of plasma proton density are accelerated in 10 minutes to a power-law intensity spectrum rolling over at 300 MeV by a 2500km s−1 shock traveling outward from 3.5r , for typical coronal conditions and low ambient wave intensities. Interacti...

We consider MHD waves as a heating source of cool cores of galaxy clusters. In particular, we focus on transverse waves (Alfvén waves), because they can propagate a longer distance than longitudinal waves (sound waves). Using MHD simulations, we found that the transverse waves can stably heat a cool core if the wave period is large enough (& 10 yr). Moreover, the longitudinal waves that are cre...

[1] Recent observations have indicated that in addition to the quasi-static acceleration of electrons in inverted V structures, auroral electrons frequently have a spectrum that is broad in energy and confined to parallel pitch angles, indicative of acceleration in lowfrequency waves. Test particle models have indicated that these electrons may be accelerated by the parallel electric fields in ...

There are in the literature several theories to explain the mass loss in stellar winds. In particular, for late-type stars, some authors have proposed a wind model driven by an outwarddirected flux of damped Alfvén waves. The winds of these stars present great amounts of dust particles which, if charged, can give rise to new wave modes or modify the pre-existing ones. In this work, we study how...