Fast Ion Transport Options in TRANSP Presented at Energetic Particle SFG Meeting, PPPL June – D. McCune

Preliminary: TRANSP Web Documentation TRANSP website: “TRANSP HELP” web page: This describes the subset of the TRANSP namelist known to interest users. –One can search for substring “difb” to get information on fast ion transport model options. This will be updated.

Anomalous Transport Options At present only “ad hoc” modeling options are available in NUBEAM and TRANSP. A Monte Carlo transport operator implements: The diffusion and velocity can be input as profile functions of time and radial flux coordinate– input “Ufile” or MDS+ signals. Can apply to beam ions and/or fusion product ions.

Transport Options (2) If “Ufile” signals are not provided, the fast ion diffusivity can be set by namelist. –Usually a step function in time. –An assumption of proportionality to electron particle diffusivity exists– probably not useful. Namelist controls allow introduction of energy dependence. –No pitch angle dependence –No spatial localization of energy dependence.

Model Applications It’s a crude, simple model– suggestions for improvement are welcome. –Some doubt about a method driven purely by prescribed input data… It has been used as a “knob” to affect global fast ion confinement, adjust neutron rate simulation to match experiment. E. Ruskov wrote papers showing upper limits on fast ion diffusion, on TFTR.