Elementary press and applications of pellet ablation in magnetically confined high temperature plasma

The hydrogen pellet injection has been expected as a fuel feeding method for thermonuclear fusion reactors. In the present paper, two elementary processes that govern particle feeding characteristics, ablation of solid hydrogen and homogenization of ablation plasma, are discussed. A solid hydrogen pellet is vaporized by heat flux from impinging ions and electrons in a hot plasma. A high-density plasmoid created from the solid hydrogen is strongly influenced by the confining magnetic field and is merged to background plasma. The production of ablation plasma from a hydrogen pellet differs so much from the plasma production by laser ablation. I addition to the physics of particles feeding by hydrogen pellet injection, diagnostic methods of the pellet ablation process and hydrogen pellet injection technologies are introduced. (J.P.N.)