A dimensionless criterion for characterizing internal transport barriers in tokamaks
A simple criterion, based on a dimensionless parameter related to drift wave turbulence stabilization and anomalous transport theory, is proposed in order to characterize the emergence and the space-time evolution of internal transport barriers (ITBs) during a tokamak discharge. The underlying physics which led us to consider the possible relevance of this parameter as a local indicator of a bifuricated plasma state is the breaking of the gyro-Bohm turbulence scaling by diamagnetic velocity shear, which has been observed in various in various numerical simulations [eg. X. Garbet and R E Waltz, Physical Plasmas 3 (1996) 1898]. The presence of an ITB is inferred when the parameter exceeds a threshold value. The main features like the emergence time, location and even dynamics of ITB's can then be summarized on a single graphical representation consistent with measurement uncertainties. The validity of such a criterion is demonstrated on the Optimized Shear (OS) database of JET in several experimental configurations. Large database analysis and real-time control of OS discharges are envisaged as the most attractive applications.
Bibliographic Reference: Report: EUR-CEA-FC-1700 EN (2000) 25 pp.
Availability: Available from Association-Euratom, Saint-Paul-Lez-Durance (FR)
Record Number: 200012746 / Last updated on: 2000-09-08
Original language: en
Available languages: en