Stability analysis of internal ideal modes in low-shear tokamaks
2007 (English)In: Physics of Plasmas, ISSN 1070-664X, Vol. 14, no 11, 110703- p.Article in journal (Refereed) Published
The stability of internal, ideal modes in tokamaks with low magnetic shear in the plasma core is analyzed. For equilibria with large aspect ratio, a parabolic pressure profile and a flat q profile in the core, an exact solution of the ideal magnetohydrodynamic (MHD) stability equations is found. The solution includes the eigenfunctions and the complete spectra of two distinctly different MHD phenomena: A family of fast-growing, Mercier-unstable global eigenmodes localized in a low-shear region with q < 1, and another, related family of stable, global eigenmodes existing in plasmas with q > 1 in the core. In the latter case the solution in addition includes one unstable eigenmode, if beta
is larger than a critical value depending on the width of the low-shear region and on the q-profile in the edge region.
Place, publisher, year, edition, pages
2007. Vol. 14, no 11, 110703- p.
eigenvalues and eigenfunctions, plasma boundary layers, plasma instability, plasma magnetohydrodynamics, plasma pressure, plasma toroidal confinement, Tokamak devices
IdentifiersURN: urn:nbn:se:uu:diva-14322DOI: 10.1063/1.2811929ISI: 000251325800003OAI: oai:DiVA.org:uu-14322DiVA: diva2:42092