Edge transport and fuelling studies via gas puff modulation in ASDEX Upgrade L-mode plasmas

Gas puff modulation experiments are performed at ASDEX Upgrade in L-mode plasmas. We model the discharge with the ASTRA transport code in order to determine transport coefficients outside of a normalized radius of rho (pol) = 0.95. The experimental data is consistent with a range of particle diffusivities and pinch velocities of the order of D = (0.20 +/- 0.13) m(2) s(-1) and v = (-1 +/- 2) m s(-1), respectively. The electron temperature response caused by the gas modulation permits to estimate also that heat diffusivity chi (e) increases almost linearly when collisionality rises due to fuelling. The fuelling particle flux is amplified by recycling, overcompensating losses.