Collisionality scaling of main-ion toroidal and poloidal rotation in low torque DIII-D plasmas

Grierson, B. A.; Burrell, K.H.; Solomon, W. M.; Budny, R.; Candy, J.

doi:10.1088/0029-5515/53/6/063010

Cited by 38 publications

(44 citation statements)

References 55 publications

(102 reference statements)

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“…1 of Ref. 6). For these reasons, the PAAR method used in this work has been extended so that it is also valid at high rotation, i.e., jṼ j=V th ¼ Oð1Þ.…”

Section: Appendix: Paar Analysis At High Rotationmentioning

confidence: 88%

“…The present work concerns comparisons between measurements and theory in the core of the plasma. In this region, some results have been shown to be inconsistent with neoclassical predictions, [6][7][8] while results from other conditions have shown better agreement. 9,10 These discrepancies demonstrate that our present understanding of plasma rotation is incomplete.…”

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confidence: 86%

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Testing neoclassical and turbulent effects on poloidal rotation in the core of DIII-D

et al. 2014

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Experimental tests of ion poloidal rotation theories have been performed on DIII-D using a novel impurity poloidal rotation diagnostic. These tests show significant disagreements with theoretical predictions in various conditions, including L-mode plasmas with internal transport barriers (ITB), H-mode plasmas, and QH-mode plasmas. The theories tested include standard neoclassical theory, turbulence driven Reynolds stress, and fast-ion friction on the thermal ions. Poloidal rotation is observed to spin up at the formation of an ITB and makes a significant contribution to the measurement of the E→×B→ shear that forms the ITB. In ITB cases, neoclassical theory agrees quantitatively with the experimental measurements only in the steep gradient region. Significant quantitative disagreement with neoclassical predictions is seen in the cores of ITB, QH-, and H-mode plasmas, demonstrating that neoclassical theory is an incomplete description of poloidal rotation. The addition of turbulence driven Reynolds stress does not remedy this disagreement; linear stability calculations and Doppler backscattering measurements show that disagreement increases as turbulence levels decline. Furthermore, the effect of fast-ion friction, by itself, does not lead to improved agreement; in QH-mode plasmas, neoclassical predictions are closest to experimental results in plasmas with the largest fast ion friction. Predictions from a new model that combines all three effects show somewhat better agreement in the H-mode case, but discrepancies well outside the experimental error bars remain.

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“…1 of Ref. 6). For these reasons, the PAAR method used in this work has been extended so that it is also valid at high rotation, i.e., jṼ j=V th ¼ Oð1Þ.…”

Section: Appendix: Paar Analysis At High Rotationmentioning

confidence: 88%

mentioning

confidence: 86%

Testing neoclassical and turbulent effects on poloidal rotation in the core of DIII-D

et al. 2014

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“…Weight functions describing FIDA diagnostics will also describe D α -based CER spectroscopy of the bulk deuterium ions [6][7][8][9][10][11] and would then also be applicable to CER spectroscopy based on impurity species [4,5] if the path of the emitter from the charge-exchange reaction to the photon emission does not curve significantly. Hence we could also show velocity-space interrogation regions of particular wavelength intervals in CER spectroscopy with our approach, estimate where in velocity space most signal comes for a given ion velocity distribution function, calculate spectra, and -perhaps the most interesting application -calculate velocity-space tomographies of bulk-ion velocity distribution functions of the emitting species.…”

Section: Cer Spectroscopy Of the Bulk Ionsmentioning

confidence: 99%

On velocity-space sensitivity of fast-ion D-alpha spectroscopy

Salewski

Geiger

Moseev

et al. 2014

Plasma Phys. Control. Fusion

123

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Abstract. The velocity-space observation regions and sensitivities in fast-ion D α (FIDA) spectroscopy measurements are often described by so-called weight functions.Here we derive expressions for FIDA weight functions accounting for the Doppler shift, Stark splitting, and the charge-exchange reaction and electron transition probabilities. Our approach yields an efficient way to calculate correctly scaled FIDA weight functions and implies simple analytic expressions for their boundaries that separate the triangular observable regions in (v , v ⊥ )-space from the unobservable regions. These boundaries are determined by the Doppler shift and Stark splitting and could until now only be found by numeric simulation.

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“…In the DIII-D data the ion poloidal velocity is of order +1 m/s to +20 km/s in the ion diamagnetic direction [Grierson, et al (2013)]. In contrast, in the ASDEX data the poloidal velocity is −1 to −2 km/s in the electron diamagnetic direction.…”

Section: Radial Electric Field E R In H-mode Transport Barriersmentioning

confidence: 99%