Malihe Omrani

In recent years, helicon plasma sources have attracted much attention from scientific centers and industry. In this regard, the power coupling is of particular importance for the production of dense plasma in these systems. Therefore, in order to achieve maximum efficiency in these types of plasma sources, it is necessary to analyze the key parameters affecting plasma power absorption such as magnetic field (50-700 G), gas pressure (1-20 mTorr), radiofrequency power (800-2200 W), and RF frequency (6.28, 13.56, 20.34, and 27.12 MHz) applied to Nagoya antenna. Finding the optimal range of these parameters is one of the key parameters in the design and construction of helicon plasma sources. Therefore, in this article, we investigate the parameters affecting the power absorption mechanisms in these types of plasma sources using a 3-D simulation of the helicon plasma source with the finite-element method. Our findings indicate that absorption mechanisms have different effects on the absorption power due to the option of the most optimal plasma parameters' value. The results show that changes in absorption power in terms of plasma density are nonlinear and show changes in the mode from E to H and eventually to W. Because of the domination of collisionless mechanism, the absorbed power increases in the pressures lower than 2 mTorr. In addition, at pressures above 2 mTorr, it increases due to the collisional mechanism. Plasma density increases linearly as the magnetic field intensity increases. The density peak is observed at the vacuum chamber edge in low magnetic fields (in the range of 65 G) which represents the Trivelpiece-Gould (TG) mode formation.