Boonyarit Chatthong and Thawatchai Onjun

pp. 719 - 725

Abstract

The locality effects on bifurcation paradigm of L-H transition phenomenon in magnetic confinement plasmas are
investigated. One dimensional thermal transport equation with both neoclassical and anomalous transports effects included
is considered, where a flow shear due to pressure gradient component is included as a transport suppression mechanism.
Three different locally driven models for anomalous transport are considered, including a constant transport model, pressure
gradient driven transport model, and critical pressure gradient threshold transport model. Local stability analysis shows that
the transition occurs at a threshold flux with hysteresis nature only if ratio of anomalous strength over neoclassical transport
exceeds a critical value. The depth of the hysteresis loop depends on both neoclassical and anomalous transports, as well as
the suppression strength. The reduction of the heat flux required to maintain H-mode can be as low as a factor of two, which
is similar to experimental evidence.

Keywords

• plasma
• tokamak
• fusion
• L-H transition
• bifurcation