Current status of elemental research on a laser fusion reactor with a liquid wall in Japan is summarized. Cascade scheme was found to be useful to obtain a continuous protective liquid LiPb layer. Formation of micro particles in a plume ablated by alpha particle heating is discussed based on experimental results obtained by backside irradiation of a lead membrane. Our numerical simulation results for formation of aerosols matched experimental results obtained with electric discharge through a thin lead membrane. Protection of beam port is described. A magnetic field generated with a pulse current successfully shields the tip of beam port from alpha particles. Tracking of cone target with diverging beam showed 0.2 m resolution at 10m separation.