Analysis of the Alfvén Activity Using FAR3d in the Stellarator Devices QPS and TJ-II

Abstract: The talk shows the work carried out by Juan Ortiz during

his PhD. It is primarily focused on the use of the gyro-fluid code FAR3d

to analyze the linear stability of Alfv´en eigenmodes (AE) in the QPS

and TJ-II devices heated by a tangential neutral beam injector (NBI).

FAR3d solves the reduced MHD equations for the thermal plasma cou-

pled with moments of the kinetic equation for the energetic particles

(EP). The presentation is structured into three main segments. First,

an introduction to the FAR3d code and its application in studying

Alfv´enic activity. Second, a theoretical analysis of the QPS stellerator

device is presented, identifying the optimal operational regime concerning NBI characteristics and potential AlfvA©nic instabilities. Third, the use of FAR3d to analyze experimental data from the TJII stellarator in Madrid is discussed, identifying the type of instabilities detected

and expanding the study to the optimization of TJII performance by

modifying the NBI parameters in a manner similar to the QPS analysis

approach.