Bernstein wave propagating obliquely to the magnetic field is excited by a coaxial antenna in a streaming plasma and detected by the interferometer system, which shows that the dispersion relation for the wave is consistent with the theoretical result. The other wave-like signal with shorter 'wavelength' is observed only on the downstream of the exciting antenna and its 'phase velocity' is appr...

We present the numerical parametric study of a reconfigurable plasma antenna array (PAA) composed of a metallic half-wavelength dipole and a set of cylindrical plasma discharges arranged in a planar square lattice. Our results, obtained with the linear embedding via Green’s operators (LEGO) method, indicate that beam-forming and beam-steering functionality can be achieved and controlled by appr...

Magnetically enhanced inductively coupled plasmas (MEICP) and helicons have complex plasma electric-field coupling between the electric field and the plasma due to the tensor conductivity and multiple-dimensional antenna segments. Computed three-dimensional electric fields and electron temperatures are presented for a helicon reactor demonstrating azimuthal asymmetries and rotations of the elec...

This paper presents the analysis of the impedance of a short dipole antenna in a cold plasma using a quasi-static approach. Two radically different current distributions on the antenna are considered and their influences on the antenna impedance are studied. These distributions include a one-dimensional (1-D) triangular distribution and a three-dimensional (3-D) exponential current distribution...

Before the 2015/2016 experimental campaign, the ASDEX Upgrade (AUG) 2-strap ICRF antennas with tungsten-coated limiters were replaced by 3-strap antennas. The main goal of the 3-strap launcher was to reduce the release of tungsten (W) in order to improve the ICRF operation, which appeared to be troublesome after the all-W wall installation [1]. In this paper, we analyse the behaviour of the 3-s...

One of the keys to successful ion cyclotron range of frequency (ICRF) heating is antenna performance. In Alcator C-Mod, we have investigated the compatibility of high power ICRF antennas with high performance plasmas and all high-Z plasma facing components, to provide operational information for future devices such as ITER. Boronization appears to be critical to control plasma radiation but it ...

A wide-frequency range (50-300 kHz) power system has been implemented for use with a new RF antenna – the “Shoelace” antenna – built to drive coherent plasma fluctuations in the edge of the Alcator C-Mod tokamak. A custom, dynamically-tunable matching network allows two commercial 1 kW, 50-Ω RF amplifiers to drive the low-impedance, inductive load presented by the antenna. This is accomplished ...