Resistive toroidal plasma spectra and power absorption from external fields

Toroidal plasmas respond to external driving fields in a way which is determined by the coupling of these fields to the spectral modes of the plasma. We have extended the toroidal resistive magnetohydrodynamic spectral code, SPECTOR, to include the effects of external fields on tokamak-like plasmas. The code is capable of determining both the stable and unstable modes and also the response to helical applied fields with arbitary mode structure. Resistivity changes the continuous regions of the ideal MHD spectrum into a set of discrete eigenvalues lying along lines in the complex frequency plane with a spacing which is related to the inverse of the square root of the magnetic Reynolds number. The close spacing means that for a particular frequency there are a large number of modes contributing to the plasma response. Results will be presented which relate the spectral distribution to the plasma response and power absorption as a function of frequency and resistivity. (orig.)