RAS Specialist Discussion Meeting on Non-equilibrium plasmas, from the X-rays to the UV: challenges for modelling

Friday 11 April 2014, 10:30-15:30

The Geological Society,Burlington House,LONDON,W1J 0BG (see MAP here) (see RAS meeting page here )

Abstract submission deadline (talks): 21 March 2014 - EXPIRED.

Sun Crab Nebula



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 .

The meeting is free to attend for RAS Members, 15 GBP for non-member (5 students) payable at the meeting.

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