AbstractThe understanding of implosion physics and the progress of relevant technologies for inertial fusion has led us to a new phase of inertial fusion research: the initiation of the construction of ignition-capable laser facilities (the US National Ignition Facility and the French Megajoule Project). This also led us to consider a new phase for Inertial Fusion Energy (IFE) research, to proceed to IFE test facilities operating at high pulse rates, once ignition and gain is demonstrated in the ignition class facilities. Many design concepts of IFE power plants have been investigated to clarify the critical issues for achieving technical and economical feasibility. R&D on the critical issues of drivers, targets and chambers for both direct and indirect-drive options have many common engineering issues together with concept-dependent issues. International exchanges and collaborations on these issues are beneficial for efficient development toward the ultimate goal of commercial use of fusion energy.