Improvements of magnetic measurements for plasma control in KSTAR tokamak

The improvements in the magnetic measurement are carried out to provide more accurate plasma parameters required for better plasma control in the KSTAR tokamak. Firstly, the large noise width in the magnetic diagnostic (MD) sensor signals (up to delta V/V = similar to 20%), which caused from the IVCC power supply being essential for sustaining high elongated plasmas, can be reduced down to similar to 1% by using commercial anti-aliasing (AA) electronic filters with the cut-off frequency f(c) of 0.86 kHz. Secondly, the time response of similar to 1.0 ms required for the fast vertical control is achieved by using new AA filter (f(c) = 2.2 kHz) which has been developed to minimize the time delay due to the previous filter. In this paper, the characteristics of the AA filters are described, and the improvements in the magnetic measurements are presented. (C) 2017 Elsevier B.V. All rights reserved.