A multi-purpose reciprocating probe drive system for studying the effect of gas-puffs on edge plasma dynamics in the ADITYA-U tokamak

TL;DR

This paper introduces a versatile high-speed reciprocating probe drive system for detailed edge plasma studies in the ADITYA-U tokamak, enabling precise, remote-controlled measurements of plasma parameters and magnetic fluctuations.

Contribution

The paper presents a novel, fully operational reciprocating probe system with interchangeable heads, enhancing plasma diagnostics in tokamak edge regions.

Findings

Fuel gas-puff affects plasma parameters up to 4 cm inside LCFS

Magnetic fluctuations measured inside LCFS

System allows precise, remote control of probe operations

Abstract

This article reports the development of a versatile high-speed reciprocating drive system (HRDS) with interchangeable probe heads to characterize the edge plasma region of ADITYA-U tokamak. This reciprocating probe drive system consisting of Langmuir and magnetic probe heads, is designed, fabricated, installed, and operated for studying the extent of fuel/impurity gas propagation and its influence on plasma dynamics in the far-edge region inside the last closed magnetic flux surface (LCFS). The HRDS is driven by a highly accurate, easy-to-control, dynamic, brushless, permanently excited synchronous servo motor operated by a PXI-commanded controller. The system is remotely operated and allows for precise control of the speed, acceleration, and distance traveled of the probe head on a shot-to-shot basis, facilitating seamless control of operations according to experimental requirements. Using this system, consisting of a linear array of Langmuir probes, measurements of plasma density, temperature, potential, and their fluctuations revealed that the fuel gas-puff impact these mean and fluctuating parameters up to three to four cm inside the LCFS. Attaching an array of magnetic probes to this system led to measurements of magnetic fluctuations inside the LCFS. The HRDS system is fully operational and serves as an important diagnostic tool for ADITYA-U tokamak.