Measurements of the tokamak safety factor profile by means of driven resonant Alfvèn waves
In the large aspect ratio approximation the resonance condition is a function of the toroidal and poloidal mode numbers (n,m), the local mass density and the safety factor q(r). The local value of q(r) can therefore be obtained directly when the central line densities are known, for which the resonance condition is satisfied at a given radius. For two identical discharges with, for example, (n,m)=(1,1) and (2,0) excitation, this can be obtained from electron line density measurements, providing the two discharges have the same effective ion mass. Safety factor profiles are plotted for discharges with and without sawtooth behaviour at various plasma currents and toroidal fields. In general the measured q profile extrapolates well to the value obtained. Results indicate a flat q-profile during sawtooth, with q close to unity in the central region.
Bibliographic Reference: Paper presented: 16th European Conference on Controlled Fusion and Plasma Physics, Venezia (IT), March 13-17, 1989
Availability: Available from (1) as Paper EN 34435 ORA
Record Number: 198910609 / Last updated on: 1994-12-01
Original language: en
Available languages: en