Broad wavenumber turbulence measurement in the same region on EAST

Abstract Future burning plasma in magnetic confinement fusion devices necessitates diagnostic for measuring broad wavenumber turbulence. The CO 2 laser collective Thomson scattering (CO 2 -CTS) system on EAST is designed mainly for electron-scale turbulence measurements. In order to extend the capability to detect ion-scale turbulence, the key challenges of light separation and signal detection have been successfully addressed by the construction of the extremely-small-angle CO 2 -CTS (E-CTS) diagnostic. This paper employs the CO 2 -CTS in conjunction with the E-CTS, enabling the simultaneous monitoring of turbulence ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mn>0.5</mml:mn> <mml:mo>&lt;</mml:mo> <mml:mrow> <mml:msub> <mml:mi>k</mml:mi> <mml:mi>θ</mml:mi> </mml:msub> </mml:mrow> <mml:mrow> <mml:msub> <mml:mi>ρ</mml:mi> <mml:mrow> <mml:mtext>s</mml:mtext> </mml:mrow> </mml:msub> </mml:mrow> <mml:mo>&lt;</mml:mo> <mml:mn>5</mml:mn> </mml:mrow> </mml:math> ) over a broader wavenumber range ( k ∼ 5–30 cm −1 ) within the gradient region ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>ρ</mml:mi> <mml:mo>∼</mml:mo> <mml:mn>0.4</mml:mn> <mml:mo>−</mml:mo> <mml:mn>0.8</mml:mn> </mml:mrow> </mml:math> ). The application of E-CTS studies the characteristics of multi-scale turbulence, including turbulence correlation and dispersion relations. This advancement will significantly enrich our experimental comprehension of tokamak turbulence.