Gyrokinetic simulation of the effect of transient fueling on plasma turbulence in ADITYA-U tokamak

TL;DR

This study uses gyrokinetic simulations to demonstrate that transient fueling via gas puffs can suppress microturbulence in ADITYA-U tokamak plasmas, thereby increasing core temperature and energy confinement time.

Contribution

It introduces a novel active control method using periodic gas puffs to suppress TEM-driven turbulence and enhance plasma confinement in tokamaks.

Findings

Gas puffs flatten the radial density profile near mid-radius.

Suppression of TEM reduces turbulence-driven heat transport.

Multiple gas puffs lead to repeated TEM suppression and improved confinement.

Abstract

The gradient-driven microturbulence in ADITYA-U tokamak plasmas has been suppressed by injecting short gas puffs. The suppression of microturbulence increases the core temperature and subsequently the energy confinement time following the gas puff. The gas injection modifies the radial density profile, making it relatively flatter near the mid-radius. Global electrostatic gyrokinetic simulations show that this modification to the radial density profile due to gas injection suppresses the existing trapped electron mode (TEM). Simulation results show that the TEM-dominated turbulence suppression reduces the turbulence-driven heat transport, leading to an increase in core temperature. Applying multiple periodic gas-puffs leads to multiple periodic events of TEM suppression, improving the overall energy confinement time, and is used as an active control mechanism to influence microturbulence in ADITYA-U tokamak.