Charging and $E×B$ rotation of ablation clouds surrounding refueling pellets in hot fusion plasmas

The finite resistivity magnetohydrodynamic code FRONTIER-MHD [R. Samulyak et al, Nucl. Fusion 47, 103 (2007)] is used to simulate the ablation rate of refueling pellets, including the novel effect of electrostatically induced $E×B$ rotation of the ablation cloud about its symmetry axis parallel to the magnetic field. The key finding is that the centrifugal force of cloud rotation pushes the cloud density radially outwards, creating a more “transparent” ablation channel. With reduced shielding, the steady state ablation rate of a deuterium pellet significantly increases from $∼35%$ to 100%, depending on the $B$-field strength. This new effect brings the ablation rate into better accord with a known theoretical scaling law, which agrees with most current experiments.