Observation of spectrum effect on the measurement of intrinsic error field on EAST

Abstract

Abstract Intrinsic error field on EAST is measured using the ‘compass scan’ technique with different n = 1 magnetic perturbation coil configurations in ohmically heated discharges. The intrinsic error field measured using a non-resonant dominated spectrum with even connection of the upper and lower resonant magnetic perturbation coils is of the order <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mstyle displaystyle="false"> <mml:mstyle displaystyle="false"> <mml:msub> <mml:mrow> <mml:mi>b</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>r</mml:mi> <mml:mn>2</mml:mn> <mml:mo>,</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msub> </mml:mstyle> <mml:mrow> <mml:mo>/</mml:mo> </mml:mrow> <mml:mstyle displaystyle="false"> <mml:msub> <mml:mi>B</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">T</mml:mi> </mml:mrow> </mml:msub> </mml:mstyle> <mml:mo>≃</mml:mo> <mml:mstyle displaystyle="false"> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:msup> </mml:mstyle> </mml:mstyle> </mml:math> and the toroidal phase of intrinsic error field is around <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mstyle displaystyle="false"> <mml:mstyle displaystyle="false"> <mml:msup> <mml:mrow> <mml:mn>60</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>°</mml:mo> </mml:mrow> </mml:msup> </mml:mstyle> </mml:mstyle> </mml:math> . A clear difference between the results using the two coil configurations, resonant and non-resonant dominated spectra, is observed. The ‘resonant’ and ‘non-resonant’ terminology is based on vacuum modeling. The penetration thresholds of the non-resonant dominated cases are much smaller than that of the resonant cases. The difference of penetration thresholds between the resonant and non-resonant cases is reduced by plasma response modeling using the MARS-F code.