An analytic formula of the second-order equilibrium beta limit for triangular-CREL DRAKONs with arbitrary pressure profile is derived. Its predictions for a parabolic pressure profile are compared with the full third-order numerical results, leading to a semi-analytic formula. The beta limits obtained here are much lower than those obtained previously; for example, for a DRAKON with straight sections and CRELs equal in length and with triangular CRELs of aspect ratio 2, the peak beta limit is 2.2%, compared to the previous result 12%. Pressure profiles with sharper boundaries have lower beta limits. The equilibrium is governed by the predominant quadrupole Pfirsch-Schliiter current. Small deviations from the CREL condition have almost no effects on the equilibrium, and thus the beta limit. Possible ways of raising the beta limit are also discussed.
1
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.