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Following the modelling of and diagnostics from fusion plasmas, the projection operator method of Mower (applied in Liouville space) is used to establish a formalism for a systematic treatment of multiphoton processes in the presence of collisions. The formalism yields a method to treat cases of great generality and is, in more specific situations and with the use of appropriate approximations, capable of producing algorithms and compact formulae. One example which can, at least in principle, be treated with relative simplicity, is the case of near resonant multiphoton transitions where radiative processes during a collision can be neglected. Other examples are multiphoton emission processes where only a limited number of photon modes is observed, the simplest case being the formation of a line shape from a cascade in which only the last-step photons are observed. Radiative processes during a collision can be treated with relative ease when the number of photons involved is small. Such processes have previously been shown to be important for a correct description of the far line wings. Results including these effects are presented for the collisional redistribution in the Lyman-(alpha) line of hydrogen.

Additional information

Authors: VOSLAMBER D, CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR)
Bibliographic Reference: Paper presented: 10th International Conference on Spectral Line Shapes, Austin (US), June 23-30, 1990
Availability: Available from (1) as Paper EN 35761 ORA
Record Number: 199110864 / Last updated on: 1994-12-02
Original language: en
Available languages: en