UK APAP Network

Plasmas permeate our Universe, being present in stellar atmospheres, interstellar gas clouds in galaxies, planetary nebulae, supernova remnants, black hole accretion disks, and so on.
Spectroscopy of all these objects has shown a richness of information, in
particular in the spectral lines that are emitted by the ions that are present in the plasmas.
In recent years, an overwhelming amount of XUV spectroscopic data have been
obtained from the satellite missions such as SOHO, Hinode, STEREO, SDO, IRIS (solar) and Chandra, XMM-Newton, HST, FUSE
(non-solar), while upcoming and future missions such as Solar Orbiter will provide no let-up.
The state of matter in each object --- the distribution of temperature and density, chemical composition --- can be determined through diagnostic analysis of spectral data in which models, incorporating the full physics of the object, confront the observations.
In addition, seismology of stellar interiors, including our sun, are a unique probe of their structure.
Spectroscopy and seismology information are fundamental for our understanding of the origin and evolution of the Universe.

Collisions of electrons and photons with atoms, ions and molecules play a fundamental role in
characterizing astrophysical plasmas, and it is therefore necessary that accurate atomic data are calculated.
It might be surprising, but a large fraction of the spectra produced by ions is still unexplored.
Large discrepancies between observations and theory are also still present.
In recent years, we have shown the need to perform accurate calculations of
electron-ion collisions for individual ions, in order to solve the large, long-standing
discrepancies between observed and calculated line intensities in collisional (astrophysical and laboratory) plasmas.
Furthermore, there is also a long standing problem concerning the elemental abundance of our sun.
It is thought to be due to our incomplete understanding of how low light emerges from deep in its interior.

We propose calculations which will enable the interpretation of spectral
data from satellites and stellar seismology which will further our understanding of the solar corona, stellar atmospheres,
supernova remnants, nebulae and stars.
With this proposal, we aim to strengthen the collaboration between
experimental, observational and theoretical research. Our work will also impact upon the magnetic fusion
program and its quest for a safe, reliable and environmentally friendly energy source.

The International effort to develop magnetic fusion as a safe, reliable and
environmentally friendly source of energy will be a key beneficiary of this work.
Magnetic fusion laboratories around the world (including JET/Culham in the UK) and especially the flagship
ITER program at Cadarache in France, make use of spectroscopic diagnostics to maximize their
control of the plasma.
The electron collision atomic data that we produce are and will be incorporated into the main fusion
modelling package (ADAS) used by these laboratories.
ADAS was and is developed and maintained by researchers at the University of Strathclyde.
The wide distribution of our basic atomic data in all major atomic databases means that
our data are also used by a wide range of laboratories and industries.