Degraded confinement and turbulence in tokamak experiments (Reprinted from Transactions of Fusion Technology, vol 33, pg 147, 1998)

After a review on the state of tokamak transport theory, the methodology to derive experimental results will be described. Examples of confinement in ohmic plasmas and the deterioration with additional heating will be given. Some examples of improved confinement modes will be discussed. Fluctuation measurements and correlation with characteristic dimensionless numbers should reveal the clue to the unexplained phenomena. Recent information on the existence of transport barriers related to the magnetic field topology can explain anomalies in electron transport.