Plasma characterization and confirmation of helicon mode of IShTAR plasma source

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.