Charge exchange effective emission coefficients
The data sets are collections of effective emission coefficients (given the mnemonic QEF) for spectrum lines emitted by ions of elements following charge transfer from neutral beam donor atoms. For most data sets, the emitting ion is hydrogen-like (following capture by the bare nucleus) and each emissivity is the sum of the emissivities of all the component lines between two principal quantum shells at the centroid wavelength. ADF12 is a derived data format, in which a collisional–radiative model has been used to determine the populations of the emitting levels relative to the population of the recombining parent ion in its ground state (typically the bare nucleus) and the donor ion (typically a neutral beam atom). Thus the emissivity coefficient is defined with respect to unit neutral donor population and unit bare nucleus receiver population and is parametrically dependent on local beam energy, ion density, ion temperature and plasma Zeff (and assumes plasma ion temperature is the same as electron temperature and electron density consistent with ion density and Zeff ).
The span of spectrum lines in an ADF12 data set always covers the visible spectral range, since the primary application of ADF12 is to visible charge exchange spectroscopy. There is an indexed data block for each spectrum line, with the coefficient data provided as separate one-dimensional scans in each parameter with respect to a reference value. Sub-directories of ADF12 are according to donor element and a two-digit year number. There are data for excited hydrogen donor states as well as ground and also for helium, lithium and sodium donors. The ADF12 data scope following closely that of the fundamental data format ADF01.