Neoclassical bootstrap currents with well controlled central seed current drive in Tokamak plasmas are investigated analytically and numerically. The analytical current scaling predicts a strong bootstrap effect in hot, high density plasmas. The Troyon limit and safety factor profiles in various small seed current cases are considered to find the optimal conditions for a large bootstrap amplification. The Troyon limited bootstrap current is very insensitive to the detailed form of the pressure profile and the beta-limit is determined by the plasma geometry alone. Regarding the current seeding, high frequency methods, like beat-waves, are proposed, which are ideal for the localized central current drive.
Current drive and bootstrap current in stellarators