Mass number identification by Alfvén wave diagnostics in hydrogen and helium plasmas in TCABR
Abstract
The mass number is obtained through the identification of the Global Alfvén (GA) wave resonances in ohmic plasma discharges in the TCABR tokamak. By comparing hydrogen and helium discharges, the composition of carbon, oxygen, and iron impurities is determined. The non-perturbative Alfvén diagnostic is used that is based on the excitation of GA waves by an external antenna fed by a low power generator, in the frequency band swept just below the minimum of the Alfvén wave continuum. Odd or even toroidal modes are excited by selecting the current phase in the two antenna modules separated by 180 degrees in the toroidal direction. The density profile, determined from cross analysis of reflectometer and interferometer data, shows impurity accumulation in the plasma core.
- Publication:
-
Physics Letters A
- Pub Date:
- March 2016
- DOI:
- 10.1016/j.physleta.2016.01.025
- Bibcode:
- 2016PhLA..380.1189P
- Keywords:
-
- Tokamak;
- Diagnostics;
- Global Alfvén wave;
- Impurity accumulation;
- Effective mass number