Current drive at plasma densities required for thermonuclear reactors

• Published in: Nature communications Vol. 1; no. 5; pp. 1 - 8
• Main Authors: Cesario, R, Amicucci, L, Cardinali, A, Castaldo, C, Marinucci, M, Panaccione, L, Santini, F, Tudisco, O, Apicella, M.L, Calabrò, G, Cianfarani, C, Frigione, D, Galli, A, Mazzitelli, G, Mazzotta, C, Pericoli, V, Schettini, G, Tuccillo, A.A
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10-08-2010; Nature Publishing Group
• Subjects: 639/766/1960/1137; deuterium; edge effect; Energy research; Experiments; Fusion; Fusion reactors; Humanities and Social Sciences; hybrids; multidisciplinary; Plasma; Power plants; Reactors; Science; Science (multidisciplinary); Temperature; Italy
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms1052

Progress in thermonuclear fusion energy research based on deuterium plasmas magnetically confined in toroidal tokamak devices requires the development of efficient current drive methods. Previous experiments have shown that plasma current can be driven effectively by externally launched radio frequency power coupled to lower hybrid plasma waves. However, at the high plasma densities required for fusion power plants, the coupled radio frequency power does not penetrate into the plasma core, possibly because of strong wave interactions with the plasma edge. Here we show experiments performed on FTU (Frascati Tokamak Upgrade) based on theoretical predictions that nonlinear interactions diminish when the peripheral plasma electron temperature is high, allowing significant wave penetration at high density. The results show that the coupled radio frequency power can penetrate into high-density plasmas due to weaker plasma edge effects, thus extending the effective range of lower hybrid current drive towards the domain relevant for fusion reactors.
Future tokamak nuclear fusion reactors depend on efficient current drive methods, but it is hard to penetrate the high-density plasma in these devices. In this paper the authors show that radio frequency waves coupled to lower hybrid plasma waves, when the peripheral temperature of the plasma is high, can penetrate the plasma core.