A Dirac-R-matrix approach in support of the interpretation of spectra from magnetically-confined plasmas and kilonovae.

The DARC (Dirac Atomic R-matrix Code) may be employed as a non-perturbative approach to electron-impact excitation/ionisation/recombination and photoionisation[1]. Fundamentally, the atomic structure and subsequent collisional rates are an integral part of subsequent collisional-radiative models and radiative transport simulations. Within the remit of this Applied Collisions session we shall consider two examples, namely the interpretation of the electro-magnetic counterpart of a neutron star merger (kilonova) GW170817 and the impurity influx from the plasma facing components of tokamak divertors. Both examples consider overlapping elements from Z=74 to Z=79 of the periodic table.

For neutron star mergers (NSMs), immediately following a NSM,physical conditions are expected to produce significant abundances of r-process elements, including the lanthanides, actinides, and platinum-group elements. Given their expected contributions to NSM spectra, both AMO theorists and experimentalists have received increasing demand to determine spectral emission and atomic data for these elements.

For magnetically-confined plasmas, tungsten has been adopted as a plasma facing material in the divertor region. It is well-known that the migration of very small concentrations of tungsten into the plasma core has the potential to quench the fusion reaction. Therefore, the erosion and impurity influx must be characterized.

Modification of the current DARC codes is required to address problems of this scale and this shall be discussed throughout the talk.

[1] connor.freeshell.org