Excitation of Global Alfvén Waves by Low RF Power on TCABR

P. G.P. Puglia, A. G. Elfimov, L. Ruchko, R. M.O. Galvão, Z. O. Guimarães-Filho, G. Ronchi, A. M.M. Fonseca, Yu K. Kuznetsov, I. C. Nascimento, A. P. Reis, W. P. De Sá, E. K. Sanada, J. H.F. Severo, V. C. Theodoro, J. I. Elizondo

Research output: Contribution to journalConference articlepeer-review

Abstract

Recent results of Global Alfvén wave (GAW) excited by external antenna and fed by low radio-frequency (RF) power (≤1kW) in tokamak TCABR are presented. The goal of this work is to develop a diagnostic tool based on the excitation of GAW using low power RF generators when the waves can be excited without perturbing the basic plasma parameters in TCABR. This method named MHD diagnostics has already been developed on other tokamaks for toroidicity induced Alfven eigenmodes as well for GAW. Two magnetic probes are used for measurements of the magnetic field perturbations in two regimes of excitation. In the first one, the fixed RF frequency is combined with gas-puffing induced density rise and relaxation (1-2)×1013/cm3 in order to meet the GAW resonance, while in the second excitation method RF frequency sweeps 2-4 MHz are applied to the relatively stable plasma density. The plasma discharges are accompanied by saw-tooth (ST) oscillations registered by Soft-X Ray diagnostics that helps in an identification of the GAW resonances due to ST density oscillations. It is found that the fixed frequency GAW resonance appears during density rise, as well during slow density reducing after stop of gas puffing. The effective mass number Aeff=1.36 is found.

Original languageEnglish
Article number012002
JournalJournal of Physics: Conference Series
Volume591
Issue number1
DOIs
StatePublished - Mar 24 2015
Externally publishedYes
Event15th Latin American Workshop on Plasma Physics, LAWPP 2014 and 21st IAEA TM on Research Using Small Fusion Devices, RUSFD 2014 - San Jose, Costa Rica
Duration: Jan 27 2014Jan 31 2014

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