Electron pressure measurements in the outer region of RFX-mod with the upgraded edge Thomson scattering diagnostic

The edge Thomson scattering (edge TS) diagnostic has been used during the last experimental campaign on the modified reversed field experiment (RFX-mod) under various plasma conditions. The optical system for spectral analysis has been modified with respect to the initial design to improve sensitivity: now it resembles the scheme of the main Thomson scattering (main TS) which includes optical delay lines, filter polychromators with APDs and waveform digitizers. The system so configured has proved to be reliable and to fulfil the experimental requirements. The spatial resolution is now 2 cm, with six measuring points in the outer plasma region at 0.7 < r/a < 1, which is only partially covered by the main TS, up to r/a < 0.8. The time synchronization of main and edge TS systems provides a full coverage of the plasma diameter and a complete pressure profile. Alternatively, the operation of the two systems with a controlled time delay allows two-time measurements of the evolution of edge T(e), n(e) and p(e) profiles in transient events such as pellet injection or dynamo relaxations.