Fully three-dimensional ideal magnetohydrodynamic stability analysis of low-n modes and Mercier modes in stellarators
The TERPSICHORE three-dimensional linear ideal magnetohydrodynamic (MHD) stability code has been extended to the full MHD equations. The new code is used to calculate the physical growth rates of nonlocal low-n modes for l = 2 torsatron configurations. A comprehensive investigation of the relation between the Mercier modes and the low-n modes has been performed. The unstable localised low-n modes are found to be correlated with the Mercier criterion. Finite growth rates of the low-n modes correspond to finite values of the Mercier criterion parameter. Near the Mercier marginal stability boundary, the low-n modes tend to be weakly unstable with very small growth rates. However, the stability of global-type low-n modes is found to be decorrelated from that of Mercier modes. The low-n modes with global structures can be more stable or more unstable than Mercier modes.
Bibliographic Reference: Article: Physics of Fluids B, Vol. 4 (1992) No. 6, pp. 1401-1411
Record Number: 199310015 / Last updated on: 1994-11-29
Original language: en
Available languages: en