Tokamak transport studies using perturbation analysis

Studies of the transport properties of tokamak plasmas using perturbation analysis are discussed. The focus is on experiments with not too large perturbations, such as sawtooth induced heat and density pulse propagation, power modulation and oscillatory gas-puff experiments. The approximations made in the standard analysis of such experiments are made explicit and are discussed. Points of agreement as well as discrepancies between different experiments and gaps in the experimental data base are highlighted. The analysis of cross-coupling between electron thermal and particle transport using simultaneous measurements of heat and density pulses in JET is discussed, as an illustration of the potentiality to measure off-diagonal elements of the transport matrix in perturbative experiments. (author)