Enhanced erosion of lithium surface with capillary porous system

摘要

Formation of lithium vapor cloud occurs above lithium surface as temperature goes up. Experiments devoted to investigating lithium vapor cloud interacting with expanding argon plasma under applied electric field have been carried out in a linear plasma device. Lithium spectrum has been characterized by utilizing optical emission spectroscopy (OES) and many emission lines of lithium atoms have been observed, including Li_670.78 nm (1.9 eV), Li_610.36 nm (3.87 eV), Li_460.30 nm (4.54 eV) and Li323.26 nm (3.83 eV). Enhanced erosion of lithium surface caused by surface adatoms was found when bias is high, its effective adatoms sublimation energy was calculated to be 1.72 eV at the high temperature through Arrhenius plot in enhanced region. The surface temperature of liquid lithium has been monitored by a thermocouple. Since incident argon ion energy has been elevated due to the applied electric field acceleration, the temperature of lithium surface will have different behaviors with different biases, and it turns out that the temperature has a linear relation with bias, about an increase of 16-17 degrees C per 5V bias voltage. By calculating evaporation power, excitation power and ionization power, indicating that at temperatures above 700-800 degrees C, heat flux dissipated in the lithium vapor can have a huge meaningful decrease. (C) 2017 Elsevier B.V. All rights reserved.