2-FLUID MAGNETOHYDRODYNAMIC SIMULATION OF CONFINEMENT OF PELLET-PRODUCED HYDROGEN CLOUDS IN HOT MAGNETIZED PLASMAS

The structure of dense particle clouds surrounding ablating hydrogen i sotope pellets is investigated, with particular emphasis on the B-perp endicular expansion, ionization, and deceleration dynamics. A time-dep endent single-temperature two-fluid one and one-half-dimensional Lagra ngian model is used in which the neutral,and ionized fluid components are allowed to move with different velocities. The expansion of the La grangian cells along the magnetic field lines is also taken into accou nt. For given ablation rates, the confinement radii and the radial dis tributions of the velocities, particle densities, magnetic field stren gth, temperature, and other flow and field properties are calculated a s functions of the background plasma parameters. The results show that collisional coupling between the neutral and ionized components is st rong enough to change the initially spherically symmetric expansion of the neutral particles to a field-aligned, funneled flow pattern, in f ull agreement with experimental observations. The calculated cloud par ameters are compared with measured data and results stemming from earl ier single-velocity models. (C) 1998 American Institute of Physics.