Investigating the effect of density variation on pitch angle scattering events of runaway electrons as observed through electron cyclotron emission diagnostic at Aditya-upgrade tokamak.

Nascent observations about the influence of kinetic instabilities on electron cyclotron emission (ECE) from runaway electrons (REs) have been detected and explored at the Aditya-Upgrade (Aditya-U) tokamak. The developed broadband ECE radiometer system offers wideband measurements by integrating several radio frequency units with a fixed intermediate frequency receiver with multiple channels, which is a novel approach to meet the needs of the localized measurements at various toroidal fields and extend the system dynamic range. The low density (n ≤ 1 × 10 m) plasma discharges at Aditya-U are consistently accompanied by a 20%-40% increase in the ECE radiometer signal amplitude within 100 µs and sporadic step-like modulations.

First results of fast visible imaging diagnostic in Aditya-U tokamak.

A Fast Visible Imaging Diagnostic (FVID) system, measuring the visible light emission spectrum (400-1000 nm) from tokamak plasma, has been installed on the Aditya-U tokamak to monitor the two-dimensional dynamics of the poloidal cross section of the plasma. In this work, we present the design and installation of the FVID system on the Aditya-U tokamak. The evolution of plasma and plasma-wall interactions is described.