Evolution of particle clouds around ablating pellets in magnetically confined hot plasmas
Currently cryogenic hydrogen isotope pellets are used for introducing fuel particles into the plasma interior in magnetic confinement fusion experiments. The spatial and time evolution of the initially low-temperature, high-density particle clouds forming around such pellets are considered, with particular attention being given to physical processes such as heating of the cloud by the energy fluxes carried by incident plasma particles, gasdynamic expansion with deceleration in the transverse direction, finite-rate ionisation and recombination processes, and magnetic field convection and diffusion. While the dynamic processes associated with the ionisation and radial confinement processes are characterised by the relatively short Alfvén time scale (microsec range), the subsequent phase of axial expansion is associated with a notably larger hydrodynamic time scale defined by the heat input and gasdynamic expansion rates (millisecond range). Data stemming from experimental measurements in toroidal confinement machines are compared with results of model calculations. Some similarities with space plasmas are briefly discussed.
Bibliographic Reference: Report: IPP 5/41 EN (1991) 19 pp.
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 199210157 / Last updated on: 1994-12-02
Original language: en
Available languages: en