  In contemporary magnetic confinement devices, the density distribution is
sensed with interferometers and actuated with feedback controlled gas injection
and open-loop pellet injection. This is at variance with the density control
for ITER and DEMO, that will depend mainly on pellet injection as an actuator
in feed-back control. This paper presents recent developments in state
estimation and control of the electron density profile for ITER using relevant
sensors and actuators. As a first step, Thomson scattering is included in an
existing dynamic state observer. Second, model predictive control is developed
as a strategy to regulate the density profile while avoiding limits associated
with the total density (Greenwald limit) or gradients in the density
distribution (e.g. neo-classical impurity transport). Simulations show that
high quality density profile estimation can be achieved with Thomson Scattering
and that the controller is capable of regulating the distribution as desired.
