Neutral-beam energy and power requirements for expanding-radius and full-bore start-up of tokamak reactors

Neutral-beam power and energy requirements are discussed for full-density, full-bore, and expanding-radius start-up scenarios in an elongated plasma as a function of beam pulse time and plasma density. A brief summary of the physics models is presented. A series of parameter surveys for start-up of a reactor plasma at constant density is analyzed. The applicability of an expanding-radius scheme to start-up of a large power-producing tokamak is outlined.