PROJECT TITLE :

Central electron temperature estimations of TJ-II neutral beam injection heated plasmas based on the soft x ray multi-foil technique

ABSTRACT:

The core electron temperature (Te0) of neutral beam heated plasmas is determined in TJ-II stellarator by using soft x ray detectors with beryllium filters of different thickness, based on the method known as the foil absorption technique. Te0 estimations are done with the impurity code IONEQ, making use of complementary information from the TJ-II soft x ray tomography and the VUV survey diagnostics. When considering the actual electron density and temperature profile shapes, an acceptable agreement is found with Thomson scattering measurements for 8 different magnetic configurations. The impact of the use of both neutral beam injectors on the Te0 measurements is addressed. Also, the behaviour of Te0 during spontaneous profile transitions is presented.