Investigation of gas puff induced fluctuation suppression in ADITYA tokamak

Abstract

An experiment aimed at investigating the cause of fluctuation suppression by gas puffing in the edge and scrape-off layer plasma of the ADITYA tokamak is reported. The fluctuation suppression is accompanied by a flattening of the radial profiles of the floating potential, plasma density and electrostatic Reynolds stress. Both the fluctuation suppression and the simultaneous reduction in particle flux occur throughout the observed region of the plasma edge. The bolometer data also show an increase in the edge radiation from 20% to 40% of the input power during the gas puff. These results indicate a significant role of edge cooling in the fluctuation suppression mechanism and are shown to be well explained in terms of a concomitant reduction in the growth rate of the interchange instability associated with the electron temperature gradient.

Drift-Alfven waves induced optical emission fluctuations in Aditya tokamak

“…Or else it may be caused by the current profile change due neutral hydrogen puffing, which reduces the magnitude of the magnetic fluctuations and hence the coupling between the drift and Alfven modes. Further, an improvement in the particle confinement time 15 has been observed during the gas puff, which indicated the transport of particle due to the drift-Alfven wave is reduced during the gas puff.…”

Invited Review Article: Gas puff imaging diagnostics of edge plasma turbulence in magnetic fusion devices

“…On the TEXTOR tokamak, there was no significant perturbation in the plasma or edge turbulence at their deuterium GPI puff rate of up to ∼4.6 × 10 20 atoms/s for ∼0.5 s. 46 On the other hand, some small tokamaks such as ADITYA have reported changes in the edge turbulence with gas puffs of ∼2 × 10 21 atoms/s correlated with a decreases in the edge electron temperature due to radiative cooling. 158,159 On other devices such as Alcator C-Mod when operating at low densities n e 0.8 × 10 20 m 3 or EAST, 87 the normal helium GPI puff of ∼10 20 atoms/s for ∼0.2 s caused a significant (≥20%) rise in plasma electron density, probably due to the recycling of helium. A similar or larger rise in density is caused when a deuterium puff is used for GPI in C-Mod.…”

Plasma flows in scrape-off layer of Aditya tokamak

“…In this paper we report first measurement of plasma flows in the SOL region of Aditya tokamak. 12 We present the measured radial profile of toroidal Mach numbers at one toroidal/poloidal location and put forward reasonable explanation of the measurements.…”

“…This is comparable to the value obtained from direct measurement. 12 It should be noted that similar equilibrium configuration may be expected in other tokamaks, where active feedback control is not used. The density profile along with temperature profile can be …”