Programme:

• 10:30-10:50 N.R. Badnell (University of Strathclyde) Atomic calculations for non-equilibrium plasmas
• 10:50-11:10 S. Preval (Leicester University) NLTE model atmospheres -- The case of hot DA white dwarfs
• 11:10-11:30 S.J. Rose (Blackett Laboratory Imperial College) Non-LTE models for high energy density plasmas
• 11:30-11:50 M. O Mullane A. Giunta, H. Summers (University of Strathclyde and RAL) Non-equilibrium effects in finite density plasmas
• 11:50-12:10 R.J.R. Williams (AWE Aldermaston) Partial LTE
• 12:10-12:30 J.W. Harris (AWE Aldermaston) Modelling high density, high temperature plasma spectra
• 12:30-12:50 Poster presentations
• 12:50-13:50 Lunch break
• 13:50-14:10 E. Dzifčáková (Astronomical Institute of the Academy of Sciences of the Czech Republic) Non-Maxwellian electron distributions and their effect on excitation and ionisation state of the plasma
• 14:10-14:30 H. Russell (IoA, University of Cambridge) Electron-ion thermal equilibration behind galaxy cluster merger shocks
• 14:30-14:50 E.H. Avrett (Harvard Smithsonian Center for Astrophysics, Cambridge, USA) Hydrogen and Helium Diffusion in Regions With a Large Temperature Gradient
• 14:50-15:10 Kosovare Olluri (Institutt for teoretisk astrofysikk, Norway) Non-equilibrium Ionisation Effects on the Density Line Ratio Diagnostics of O IV
• 15:10-15:30 J.Dudik (DAMTP, University of Cambridge) Diagnostics of non-Maxwellian electron distributions for the solar corona

Posters:

• L. Fernandez Menchero: R-matrix electron-impact excitation data for the Mg-like iso-electronic sequence
• F. G. Fulgencio: Impurity profiles in turbulent temperature and density fields
• G. Del Zanna, H. Mason: the CHIANTI atomic database

This specialist discussion meeting aims to review our current understanding of non-equilibrium effects such as time-dependent ionization, non-Maxwellian particle distributions and non-coronal density effects, which are ubiquitous in laboratory and astrophysical plasmas.

In the past, we have learned a great deal (in particular on the identification of spectral lines and the testing of atomic calculations) from laboratory XUV spectroscopy, where non-equilibrium effects are often dominant. A significant effort on atomic data calculations and modelling (ADAS) has been produced for the fusion community, but little is known by the wider astrophysical community. In recent years, a wealth of XUV spectra of astrophysical plasmas has been obtained: observations with SOHO and RHESSI have revealed the true dynamic nature of the Sun, our own unique plasma laboratory. It is most likely that non-equilibrium effects play an important role in the solar atmosphere, in particular where strong temperature gradients/flows are present such as the transition region. The solar IRIS spectroscocopic mission, launched in 2013, is providing order of magnitude advanced observations, and non-equilibrium effects are likely to be dominant. HST, FUSE, XMM-Newton and Chandra have probed more extreme plasma environments from supernova remnants and stellar atmospheres through to black hole accretion disks and AGN. In such plasmas, non-equilibrium effects such as time-dependent ionization, non-Maxwellian particle distributions and non-coronal density effects are becoming points of focus for modellers.

Future UV and X-ray spectroscopy will be sensitive enough to routinely observe non-equilibrium effects in solar and astrophysical plasmas. It is therefore essential that modelling efforts be capable of both reproducing these effects and predicting diagnostics for observers.

The challenge for plasma modellers lies in piecing together the necessary atomic data - excitation, ionization, recombination rates - and then interfacing with kinetic/fluid codes to reproduce the observed emissions. Results from these models can then pave the way for new instrumentation that can fully test the models and lead to a better understanding of fundamental plasma processes.

Communication between the atomic physics, the laboratory plasma and the astrophysics communities is thus a crucial part of the research effort. The present meeting will provide a forum for scientists from these communities to present recent advances in their fields with regard non-equilibrium effects. Contributions from relevant areas such as atomic data calculations and provisions, plasma modelling, and direct observation of dynamic phenomena are encouraged.

Tea and coffee will be provided between 10:00 and 10:30 and again after the meeting at 15:30 in the Lower Library of the Geological Society for those attending the Open (Monthly A&G) Meeting of the Royal Astronomical Society .

Organisers: Dr Giulio Del Zanna, Dr Helen Mason (University of Cambridge), Prof Nigel Badnell (University of Strathclyde)

Page last updated: 22 Mar 2014 by Giulio Del Zanna