Evolution of high-density particle clouds in magnetically confined plasmas
The spatial and time evolution of initially low-temperature high-density particle clouds are studied in magnetically confined hot plasmas, such as those produced by ablating cryogenic hydrogen pellets in fusion machines. The Lagrangian approximation used makes it possible to take into account all relevant physical processes that affect the radial expansion and deceleration of the cloud particles, including the change of the magnetic field topology. The results show the existence of a distinct structure in the ablatant cloud surrounding an ablating pellet, i.e. a hollow temperature profile coupled to a peaked density profile in the plane normal to the magnetic field direction. The lifetime of this structure is measured on hydrodynamic time-scales. The basic properties of the cloud, such as its radial extent, average temperature and bulk density are functions of the pellet ablation rate, the parameters of the background plasma, and the magnetic field strength applied. Simple analytical or ad hoc descriptions of this functionality, as in present ablation models, do not seem possible.
Bibliographic Reference: Report: IPP 5/33 EN (1990) 62 pp.
Availability: Available from Max-Planck-Institut für Plasmaphysik, 8046 Garching bei München (DE)
Record Number: 199110257 / Last updated on: 1994-12-02
Original language: en
Available languages: en