Completely bootstrapped tokamak

Numerical simulations of the evolution of large-scale magnetic fields have been developed using a mean-field Ohm’s law. The Ohm’s law is coupled to a Δ′ stabilty analysis and a magnetic island growth equation in order to simulate the behavior of tokamak plasmas that are subject to tearing modes. In one set of calculations, the magnetohydrodynamic (MHD)-stable regime of the tokamak is examined via the construction of an li -qa diagram. The results confirm previous calculations that show that tearing modes introduce a stability boundary into the li -qa space. In another series of simulations, the interaction between tearing modes and the bootstrap current is investigated. The results indicate that a completely bootstrapped tokamak may be possible, even in the absence of any externally applied loop voltage or current drive.