Electron Internal Transport Barriers and Magnetic Topology in the Stellarator TJ-II

3D effects on transport and plasma control in the TJ-II stellarator

Doppler reflectometer system in the stellarator TJ-II.

A Doppler reflectometer system has recently been installed in the stellarator TJ-II. The system is optimized for the Q-band (33-50 GHz) and the high-curvature plasmas produced in TJ-II. The launch angle of the microwave beam can be controlled by a steerable mirror to obtain angles between +/-20 degrees enabling the measurement of perpendicular wave numbers in the range of 3-15 cm(-1). The avail...

Global Plasma Oscillations in Electron Internal Transport Barriers in TCV

Global plasma oscillations have been observed in the Tokamak à Configuration Variable (TCV; R/a=0.88m/ 0.25m, BT<1.54T) in reversed magnetic shear discharges (fully non-inductive driven) with electron Internal Transport Barriers (eITBs). These slow oscillations involve the electron temperature and density and the plasma current. The triggering mechanism is the periodic destabilisation and stabi...

Probing the edge ion temperature by passive Doppler spectroscopy in the TJ-II stellarator

We report on the measurement of the edge ion temperature in TJ-II plasmas, heated by electron cyclotron waves and neutral beam injection, using passive spectroscopy of impurity ions in low ionization stages. The measurements, which provide both temporal and some spatial resolution, offer some advantages over more intrusive or more sophisticated methods. The capabilities and limitations of this ...

Ion Heating in transitions to CERC in the Stellarator TJ-II

F. Castejón1,4, L.A. Fernández2,4,V. Martin-Mayor2,4, A. Tarancón3,4, J.L. Velasco3,4, CX group1 1 Laboratorio Nacional de Fusión—Asociación Euratom/Ciemat, 28040-Madrid, Spain 2 Dep. de Física Teórica I. Universidad Complutense de Madrid, 28040-Madrid, Spain. 3 Dep. de Física Teórica. Universidad de Zaragoza, 50009-Zaragoza, Spain 4 BIFI: Instituto de Biocomputación y Física de Sistemas Comple...