Observation and particle simulation of vaporized W, Mo, and Be in PISCES-B plasma for vapor-shielding studies

Highlights: • Optical decay lengths were measured for W, Mo, Be vapor in a steady-state plasma. • Observation indicated an efficient plasma cooling for Be vapor but not for others. • Ionization m.f.p. and re-deposition may explain these differences. - Abstract: Interactions of Tungsten (W), Molybdenum (Mo), and Beryllium (Be) vapors with a steady-state plasma were studied by the PISCES-B liner plasma experiments as well as Particle-In-Cell (PIC) simulations for the understanding of vapor-shielding phenomena. Effective cooling of the plasma by laser-generated Be vapor was observed in PISCES-B. On the other hand, no apparent cooling was observed for W and Mo vapors. The PIC simulation explains these experimental observations of the difference between low-Z and high-Z vapors. Decrease of electron temperature due to the vapor ejection was observed in case of a simulation of the Be vapor. As for the W vapor, it was found that the plasma cooling is localized only near the wall at a higher electron density plasma (∼ 10¹⁹ m⁻³). On the other hand, the appreciable plasma cooling can be observed in a lower density plasma (∼10¹⁸ m⁻³) for the W vapor.