TJ-II: Validation of neutral beam current drive: Difference between revisions

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density control purposes. Plasmas with co-NBI (NBI1) and counter-NBI (NBI2), as well as plasmas with balanced injection (NBI1+NBI2), will be explored. The level of optimum ECRH power will be determined depending  
density control purposes. Plasmas with co-NBI (NBI1) and counter-NBI (NBI2), as well as plasmas with balanced injection (NBI1+NBI2), will be explored. The level of optimum ECRH power will be determined depending  
on the operation conditions considering that moderate electron temperature (below 800 keV) are desirable to favour shorter stabilization times. Using off-axis ECRH injection may also help to reduce L/R time.  
on the operation conditions considering that moderate electron temperature (below 800 keV) are desirable to favour shorter stabilization times. Using off-axis ECRH injection may also help to reduce L/R time.  
The measured toroidal current will be compared to the computational/numerical estimates of the toroidal current generated by both neutrals beams once the bootstrap current contribution is removed.


Since both bootstrap and NBCD are contributing to the toroidal plasma current, the validation of NBCD needs first an estimation of the bootstrap contribution. Validating bootstrap current is a long standing  
However, since both bootstrap and NBCD are contributing to the toroidal plasma current, the validation of NBCD needs first a numerical computation of the bootstrap contribution, ideally with a validated tool.  
issue in TJ-II ECRH plasmas. Experimental proposals devoted to this task (http://fusionwiki.ciemat.es/wiki/TJ-II:Validation_of_bootstrap_predictions) have been unsuccessful because of the difficulties encountered to achieve pulses long enough to observe current stabilization.      
Validating bootstrap current is a long standing issue in TJ-II ECRH plasmas. Experimental proposals devoted to this task have been unsuccessful because of the difficulties encountered to achieve pulses long enough to observe current stabilization. Two day are requested to carry out this proposal. In its first part, and following the procedure described in http://fusionwiki.ciemat.es/wiki/TJ-II:Validation_of_bootstrap_predictions (Velasco et al.), we will
 
carry out an attempt to achieve long ECRH pulses, looking for a current stabilization phase, in order to fulfill as best the possible the goals detailed in the proposal by Velasco et al. If proved unfeasible, we will switch to NBI plasma and carry out the rest of the experiments.
The measured toroidal current will be compared to the computational/numerical estimates of the toroidal current generated by both neutrals beams once the bootstrap current contribution is removed.


== International or National funding project or entity ==
== International or National funding project or entity ==
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