Description
The Resonant Antenna Ion Device (RAID) is a linear, steady-state plasma device operated at the Swiss Plasma Center. It is dedicated to research on basic helicon physics, tokamak-edge plasma phenomena, and validation of spectroscopic plasma techniques for fusion applications, including state-of-the-art laser spectroscopy measurements.
The RAID device is equipped with an extensive set of plasma diagnostics, which provide high precision and accuracy (gigahertz interferometry), high spatial resolution (Thomson scattering), and the ability to cover the entire volume of the plasma column (movable Langmuir probes). These diagnostics thus allow precise and reliable mappings of plasma parameters, which are fundamental for research on transport phenomena and helicon physics.
In this contribution, we present experiments performed in different conditions (e.g. different antenna power and background magnetic field) and in different gases (hydrogen, deuterium, helium, argon) under adjustable pressure. While the electron density profiles established in the different plasmas appears very similar, the peak density, as well as the electron temperature profile shape, are significantly different. The observed effects may result from the interplay between helicon propagation and power deposition on the one hand and transport processes on the other hand. A comparative analysis of the different plasmas was used to investigate the complex interaction of these mechanisms. We will discuss how this result could improve our understanding of the way in which the energy is deposited and transposed through the plasma.