Plasma characterization and confirmation of helicon mode of IShTAR plasma source

TL;DR

This paper confirms the helicon mode in the IShTAR plasma source, characterizes plasma parameters, and optimizes conditions to achieve high-density plasma for improved ICRF wave interaction studies.

Contribution

It provides the first confirmation of helicon mode in the IShTAR plasma source and details the plasma characterization and optimization process.

Findings

Helicon mode confirmed at magnetic fields below 35 mT.

Plasma density optimized at higher magnetic fields.

Characterized plasma parameters include electron temperature, density, and potential.

Abstract

IShTAR (Ion cyclotron Sheath Test ARrangement) is a dedicated test facility to investigate the interaction of ICRF wave and plasma at the Max-Planck Institute for Plasma Physics in Garching, Germany. Plasma is provided by a plasma source (length= 0.1m, diameter = 0.4m) and it is responsible to create the necessary plasma environment in front of the ICRF antenna. The source is equipped with a helical antenna and designed to reach the mode of discharge. Previously there was no confirmation that this source can reach helicon mode of discharge. However, it is important for such a source to reach the helicon mode of discharge to work with its full capacity and to produce high-density plasma. To achieve helicon mode of discharge for this source a detailed study was carried out. Characterization of plasma parameters (i.e. electron temperature, density, and plasma potential) followed by the implementation of a global model of particle and power balance has been made. The existence of helicon mode confirmed at lower magnetic fields (B <35 mT). To get the highest possible plasma density, the optimization of the plasma source is presented to reach helicon mode at the highest available magnetic field.