Theory of a high-n toroidicity-induced shear Alfvén eigenmode in tokamaks
G. Y. Fu
Center for Fusion Engineering and Institute for Fusion Studies, The University of Texas at Austin, Austin, Texas 78712
C. Z. Cheng
Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543
(Received 12 July 1989; accepted 19 January 1990)
Ahigh-n WKB-ballooning mode equation is employed to study toroidicity-induced shearAlfvén eigenmodes (TAE) in s- space, where s=(r/q)(dq/dr) is themagnetic shear and =(2Rq2/B2)(dp/dr) is the normalized pressure gradient fortokamak plasmas. In the ballooning mode first stability region, TAEmodes are found to exist only for less thansome critical value c. It is found that these TAEmodes reappear in the ballooning mode second stability region forbands of values. The global envelope structures of theseTAE modes are studied by the WentzelKramersBrillouin (WKB) method andare found to be bounded radially if the local modefrequency has a maximum in radius.
Physics of Fluids B: Plasma Physics is copyrighted by The American Institute of Physics.