TJ-II:Turbulence properties near a rational surface: Difference between revisions

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In previous work, we have established that the intermittence parameter C(1) varies in a systematic way near rational surfaces<ref>B. Carreras, L. García, J. Nicolau, B. van Milligen, U. Hoefel, M. Hirsch, and the TJ-II and W7-X Teams. ''Intermittence and turbulence in fusion devices''. Plasma Phys. Control. Fusion, 62:025011, 2020.</ref>. This was found to be the case both in a numerical model of resistive MHD turbulence, and confirmed using data from the W7-X stellarator. Hence, the intermittence parameter provides an indirect diagnostic of the magnetic configuration.
In previous work, we have established that the intermittence parameter C(1) varies in a systematic way near rational surfaces<ref>B. Carreras, L. García, J. Nicolau, B. van Milligen, U. Hoefel, M. Hirsch, and the TJ-II and W7-X Teams. ''Intermittence and turbulence in fusion devices''. Plasma Phys. Control. Fusion, 62:025011, 2020.</ref>. This was found to be the case both in a numerical model of resistive MHD turbulence, and confirmed using data from the W7-X stellarator. Hence, the intermittence parameter provides an indirect diagnostic of the magnetic configuration.


In more recent work, the iota scan experiments of 2013<ref>B.Ph. van Milligen et al., Parallel and perpendicular turbulence correlation length in the TJ-II stellarator. Nucl. Fusion, 53:093025 (2013)</ref> were revisited, and a remarkably detailed confirmation of this phenomenon was obtained<ref>B. P. van Milligen, B. Carreras, L. García, and C. Hidalgo. ''The localization of low order rational surfaces based on the intermittence parameter in the TJ-II stellarator''. Nucl. Fusion, 60:056010, 2020.</ref>. The latter paper also suggested that a radial electric field (i.e., poloidal rotation) may affect the intermittence parameter significantly.
In more recent work, the iota scan experiments of 2013<ref>B.Ph. van Milligen et al., ''Parallel and perpendicular turbulence correlation length in the TJ-II stellarator''. Nucl. Fusion, 53:093025 (2013)</ref> were revisited, and a remarkably detailed confirmation of this phenomenon was obtained<ref>B. P. van Milligen, B. Carreras, L. García, and C. Hidalgo. ''The localization of low order rational surfaces based on the intermittence parameter in the TJ-II stellarator''. Nucl. Fusion, 60:056010, 2020.</ref>. The latter paper also suggested that a radial electric field (i.e., poloidal rotation) may affect the intermittence parameter significantly.
In the present experiment, we therefore plan to repeat the iota scan experiments while applying a radial electric field, induced via probe biasing.
In the present experiment, we therefore plan to repeat the iota scan experiments while applying a radial electric field, induced via probe biasing.