Ignited spherical tokamaks and plasma regimes with LiWalls

Basic requirements of the fusion power reactor and its development are outlined. The notion of operational power reactor regime (OPRR) is introduced explicitly for the first time in order to distinguish it from the relatively short ignition phase of the reactor operation. Development of OPRR is intrinsically linked to two basic technology objectives, i.e., development of the first wall (FW) and the tritium cycle (TC). The paper reveals an existing fundamental gap in the reactor development path associated with the lack of necessary amounts of tritium for the reactor design development. In this regard, low recycling regimes with a plasma limited by a lithium wall surface suggest enhanced stability and energy confinement, both necessary for tokamak power reactors. These regimes also could make ignition and OPRR feasible in compact tokamaks. Ignited spherical tokamaks (IST), self-sufficient in the bootstrap current, are introduced as a necessary interim step for development OPRR-FW-TC for the power reactors.