Discrimination between magnetic shear and toroidal electric field effects in TJ-II plasmas

• Date: 2002
• Main Authors: López-Bruna, D., Romero, J. A., Castejón, F., Estrada, T., Ascasíbar, E.
• Format: Article
• Language: English
• Published: Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2002
• Series: Вопросы атомной науки и техники
• Subjects: Magnetic confinement
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/80264
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Discrimination between magnetic shear and toroidal electric field effects in TJ-II plasmas / D. López-Bruna, J. A. Romero, F. Castejón, T. Estrada, E. Ascasíbar // Вопросы атомной науки и техники. — 2002. — № 4. — С. 51-53. — Бібліогр.: 6 назв. — англ.

The response of TJ-II plasmas to an induced toroidal electric field, Eǿ , was studied in past experiments with the aid of Ohmic inducted current. It was found that positive induced plasma current, Ip, degrades the confinement while negative Ip improves it. Candidates to provide a physical explanation are Eǿ itself and the plasma current via magnetic shear modification. A movable mirror in an electron Cyclotron Heating line of TJ-II permits varying the refraction index of the heating wave, N||, thus allowing for non inductive electron cyclotron current drive (ECCD) up to Ip ≈ ±1 kA. Comparing discharges without and with ECCD (changing shear but not Eǿ ) but sharing the same transformer action (changing both shear and Eǿ ), magnetic shear and electric field effects can be discriminated in time. It has been found that plasma response with ECCD is delayed respect to the transformer switch-on time, clearly pointing to shear effects. Effects related to Eǿ alone, if they exist, are weaker.