Crynodeb
Aims. We aim to investigate the nature of dissipative instability appearing in a prominence planar thread filled with partially ionised plasma in the incompressible limit. The importance of partial ionisation is investigated in terms of the ionisation factor and the wavelength of sausage and kink waves propagating in the slab.
Methods. In order to highlight the role of partial ionisation, we have constructed models describing various situations we can meet in solar prominence fine structure. Matching the solutions for the transversal component of the velocity and total pressure at the interfaces between the prominence slab and surrounding plasmas, we derived a dispersion relation whose imaginary part describes the evolution of the instability. Results were obtained in the limit of weak dissipation. We have investigated the appearance of instabilities in prominence dark plumes using single and twofluid approximations.
Results. Using simple analytical methods, we show that dissipative instabilities appear for flow speeds that are less than the KelvinHelmholtz instability threshold. The onset of instability is determined by the equilibrium flow strength, the ionisation factor of the plasma, the wavelength of waves and the ionneutral collisional rate. For a given wavelength and for ionisation degrees closer to a neutral gas, the propagating waves become unstable for a narrow band of flow speeds, meaning that neutrals have a stabilising effect. Our results show that the partially ionised plasma describing prominence dark plumes becomes unstable only in a twofluid (charged particlesneutrals) model, that is for periods that are smaller than the ionneutral collision time.
Conclusions. The present study improves our understanding of the complexity of dynamical processes and stability of solar prominences and the role partial ionisation in destabilising the plasma. We showed the necessity of twofluid approximation when discussing the nature of instabilities: waves in a single fluid approximation show a great deal of stability. Our results clearly show that the problem of partial ionisation introduces new aspects of plasma stability with consequences on the evolution of partially ionised plasmas and solar prominences, in particular
Methods. In order to highlight the role of partial ionisation, we have constructed models describing various situations we can meet in solar prominence fine structure. Matching the solutions for the transversal component of the velocity and total pressure at the interfaces between the prominence slab and surrounding plasmas, we derived a dispersion relation whose imaginary part describes the evolution of the instability. Results were obtained in the limit of weak dissipation. We have investigated the appearance of instabilities in prominence dark plumes using single and twofluid approximations.
Results. Using simple analytical methods, we show that dissipative instabilities appear for flow speeds that are less than the KelvinHelmholtz instability threshold. The onset of instability is determined by the equilibrium flow strength, the ionisation factor of the plasma, the wavelength of waves and the ionneutral collisional rate. For a given wavelength and for ionisation degrees closer to a neutral gas, the propagating waves become unstable for a narrow band of flow speeds, meaning that neutrals have a stabilising effect. Our results show that the partially ionised plasma describing prominence dark plumes becomes unstable only in a twofluid (charged particlesneutrals) model, that is for periods that are smaller than the ionneutral collision time.
Conclusions. The present study improves our understanding of the complexity of dynamical processes and stability of solar prominences and the role partial ionisation in destabilising the plasma. We showed the necessity of twofluid approximation when discussing the nature of instabilities: waves in a single fluid approximation show a great deal of stability. Our results clearly show that the problem of partial ionisation introduces new aspects of plasma stability with consequences on the evolution of partially ionised plasmas and solar prominences, in particular
Iaith wreiddiol  Saesneg 

Rhif yr erthygl  A78 
Tudalennau (oi)  111 
Nifer y tudalennau  11 
Cyfnodolyn  Astronomy and Astrophysics 
Cyfrol  603 
Dynodwyr Gwrthrych Digidol (DOIs)  
Statws  Cyhoeddwyd  10 Gorff 2017 
Ôl bys
Gweld gwybodaeth am bynciau ymchwil 'Dissipative instability in a partially ionised prominence plasma slab'. Gyda’i gilydd, maen nhw’n ffurfio ôl bys unigryw.Proffiliau

Balazs Pinter
 Cyfadran Busnes a’r Gwyddorau Ffisegol, Ffiseg  Senior Lecturer
Unigolyn: Dysgu ac Ymchwil