Fast neutral pressure measurements in NSTX

Several fast neutral pressure gauges have been installed on the National Spherical Torus Experiment (NSTX) to measure the vessel and divertor pressure during inductive and coaxial helicity injected plasma operations. Modified, Princeton divertor experiment-type Penning gauges have been installed on the upper and lower divertors. Neutral pressure measurements during plasma operations from these and from two shielded fast microion gauges at different toroidal locations on the vessel midplane are described. A new unshielded ion gauge, referred to as the in-vessel neutral pressure gauge is under development.