Eur. Phys. J. D (2012) 66: 213
https://doi.org/10.1140/epjd/e2012-30283-1

Regular Article

Suppression of MHD activity with limiter biasing in the HT-7 tokamak

¹ Department of Applied Physics, Donghua University, Shanghai 201620, P.R. China
² Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, P.R. China

^a e-mail: hwlu@dhu.edu.cn

Received: 2 May 2012
Received in final form: 2 June 2012
Published online: 16 August 2012

Abstract

We report here the first preliminary results of our limiter biasing experiments performed in the HT-7 tokamak. For this study, a limiter biasing system was designed, constructed and installed on the HT-7 tokamak. When a positive voltage was applied to the poloidal limiter, we observed a significant improvement in gross global particle confinement, as confirmed by the associated changes of the ratio between the line-averaged electron density and the Halpha radiation level. A significant decrease in the ECE emission and significant increases in the plasma density, XUV bolometer emission and soft X-ray (SXR) emission are also observed. Furthermore the amplitude of Magnetohydrodynamic activity can be totally suppressed when a large enough biasing is applied to the limiter in the phases of current flat-top, current ramp-down and disruptions.