On May 16–18, 1990, an Advisory Group Meeting on "Atomic and Molecular Data for Metallic Impurities in Fusion
Plasmas" was organized by the Atomic and Molecular Data Unit of the International Atomic Energy Agency and held in
Vienna, Austria. The objectives of the Meeting were to review the status of atomic collision data for the most important fusion
plasma metallic impurities (Ti, Cr, Fe and Ni), to identify the gaps in the database in relation to the data needs of the current
fusion research and reactor design work, and to report on recent original cross section calculations and measurements for
the collision processes of these ions. The scope of the meeting included the following collision processes:
(a) Electron collisions with Tiq+, Crq+, Feq+ and Niq+ ions (excitation, ionization, radiative and dielectronic recombination);
(b) Collisions of Tiq+, Crq+, Feq+ and Niq+ ions with H, H2, and He (total and state-selective electron capture, excitation,
ionization and dissociative processes with H2).
The meeting was attended by fifteen participants covering almost uniformly the various collision processes, energy ranges
and research methods (theoretical and experimental). In the area of electron-ion collision processes, extensive reviews of the
current research and cross section data situation have been presented by Y Hahn (on radiative and dielectronic recombination),
D Gregory (on excitation) and A Muller (on ionization). Contributions regarding the cross sections and/or reaction rates
of many specific processes were given by N Badnell, K Berrington, M Bitter, R E H Clark, A Muller and V P Shevelko.
V A Abramov provided a comparison of the electron-impact excitation data, evaluated by several groups, and demonstrated
their consistency in the majority of analyzed cases.
In the area of heavy-particle collision processes, the research and database situation was reviewed by H B Gilbody.
Original cross section information for specific heavy-particle collision processes was presented by H Cederquist, W Fritsch,
R E Olson, K Katsonis and G L Yudin.
The present Topical Issue of Physica Scripta contains the contributions presented at the meeting with the exception of the
presentation of V A Abramov. The reports of the Working Groups, established at the meeting to critically evaluate the
available data and to identify the gaps in the database, are also included in this volume. An appropriate introductory comment by the Guest Editor on the impurity sources and the role of impurity collision processes in fusion plasmas is also added.
On behalf of the International Atomic Energy Agency, I take this opportunity to thank the participants of the
Advisory Group Meeting for their dedicated work and valuable contribution to this international endeavour and for their co-operativeness in the course of preparation of this volume.