title: Probability of statistical L-H transition in tokamaks.
abstract: A statistical model for the bifurcation of the radial electric field Er is analyzed in view of describing L-H transitions of tokamak plasmas. Noise in microfluctuations is shown to lead to random changes of Er if a deterministic approach allows for more than one solution. The probability density function for and the ensemble average of Er are obtained. The L-to-H and the H-to-L transition probabilities are calculated, and the effective phase limit is derived. Because of the suppression of turbulence by shear in Er, the limit deviates from Maxwell's rule.
authors.affiliation: Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580, Japan.
authors.forename: Sanae-I
authors.initials: SI
authors.lastname: Itoh
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Itoh
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Toda