H. Raj | Searcharxiv

arXiv2026

Effect of LH and ECR waves on plasma parameters in ADITYA Upgrade tokamak

The plasma discharges in ADITYA Upgrade Tokamak are produced by means of transformer action, in which Ohmically created plasma is driven by means of a secondary loop voltage. Due to reduction of plasma resistivity after a certain level of plasma temperature, Ohmic heating becomes poor and further achievement of temperature needs other heating techniques. ADITYA-U tokamak is facilitated with a 42 GHz-500 kW Electron Cyclotron Resonant Heating (ECRH) system. Also, there is a Lower Hybrid Current Drive (LHCD) system installed and operated at 3.7 GHz for driving non-inductive plasma current followed by the Ohmic current drive. Though an eventual impact in the rise of plasma temperature and plasma current due to the application of ECRH and LHCD respectively are very obvious, their energy coupling with the plasma results in several interesting outcomes in a number of experimentally measured plasma parameters. The present work addresses such impactful observations that are noticed and reported for the first time in ADITYA-U Tokamak.

physics.plasm-ph↗

arXiv2025

Effect of convective transport in edge/SOL plasmas of ADITYA-U tokamak

The 2-D edge plasma fluid transport code, UEDGE has been used to simulate the edge region of circular limiter plasmas of ADITYA-U for modelling the measured electron density profile. The limiter geometry of ADITYA-U has been introduced in the UEDGE code, which is primarily developed and used for divertor configuration. The computational mesh defining the limiter geometry is generated by a routine developed in-house, and has successfully been integrated with the UEDGE code to simulate the edge plasma parameters of ADITYA-U. The radial profiles of edge and scrape-off layer (SOL) electron density, ne and temperature are obtained from the simulations and used to model the measured ne profile using Langmuir probe array. It has been found that a convective velocity, vconv. is definitely needed in addition to the constant perpendicular diffusion coefficient, D throughout the edge and SOL regions to model the edge ne profile. The obtained vconv. is inward and radially constant with a value of 1.5 m/s and the radially constant D is ~ 0.2 m 2/s. The value of D ~ 0.2 m2/s is found to be much less than fluctuation induced diffusivities and lies in-between the neoclassical diffusivity and Bohm diffusivity estimated in the edge-SOL region of ADITYA-U tokamak. Furthermore, the transport of radial electron heat flux is found to be maximizing near the limiter tip location in the poloidal plane.

physics.plasm-ph↗