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61. Gyrokinetic simulations of momentum flux parasitic to free-energy transfer

Author(s):
Stoltzfus-Dueck, T; Hornsby, W A; Grosshauser, S R
Abstract:
Ion Landau damping interacts with a portion of the E×B drift to cause a non-diffusive outward flux of co-current toroidal angular momentum. Quantitative evaluation of this momentum flux requires nonlinear simulations to determine fL, the fraction of fluctuation free energy that passes through ion Landau damping, in fully developed turbulence. Nonlinear gyrokinetic simulations with the GKW code confirm the presence of the systematic symmetry-breaking momentum flux. For simulations with adiabatic electrons, fL scales inversely with the ion temperature gradient, because only the ion curvature drift can transfer free energy to the electrostatic potential. Although kinetic electrons should in principle relax this restriction, the ion Landau damping measured in collisionless kinetic-electron simulations remained at low levels comparable with ion-curvature-drift transfer, except when magnetic shear was strong. A set of simulations scanning the electron pitch-angle scattering rate showed only a weak variation of fL with the electron collisionality. However, collisional-electron simulations with electron temperature greater than ion temperature unambiguously showed electron-curvature-drift transfer supporting ion Landau damping, leading to a corresponding enhancement of the symmetry-breaking momentum flux.
Type:
Dataset
Issue Date:
2022

62. Identification of a non-axisymmetric mode in laboratory experiments searching for standard magnetorotational instability

Author(s):
Wang, Yin; Gilson, Erik P.; Ebrahimi, Fatima; Goodman, Jeremy; Caspary, Kyle J.; Winarto, Himawan W.; Ji, Hantao
Abstract:
This dataset provides the source data of figures in the main text of the paper "Identification of a non-axisymmetric mode in laboratory experiments searching for standard magnetorotational instability" accepted by Nature Communications.
Type:
Dataset
Issue Date:
2022

63. Initial Results from Boron Powder Injection Experiments in WEST Lower Single Null L-mode Plasmas

Author(s):
Bodner, Grant; Gallo, Alberto; Diallo, Ahmed; Lunsford, Robert; Moreau, Philippe; Nagy, Alex; Pellissier, Francis-Pierre; Guillemaut, Christophe; Gunn, James; Bourdelle, Clarisse; Desgranges, Corinne; Manas, Pierre; Bortolon, Alessandro; Klepper, Christopher; Tsitrone, Emanuelle; Unterberg, Ezekial; Vermare, Laure
Abstract:
Using a recently installed impurity powder dropper (IPD), boron powder (< 150 μm) was injected into lower single null (LSN) L-mode discharges in WEST. IPDs possibly enable real-time wall conditioning of the plasma-facing components and may help to facilitate H-mode access in the full-tungsten environment of WEST. The discharges in this experiment featured Ip = 0.5 MA, BT = 3.7 T, q95 = 4.3, tpulse = 12–30 s, ne,0 ~ 4×1019 m-2, and PLHCD ~ 4.5 MW. Estimates of the deuterium and impurity particle fluxes, derived from a combination of visible spectroscopy measurements and their corresponding S/XB coefficients, showed decreases of ~ 50% in O+, N+, and C+ populations during powder injection and a moderate reduction of these low-Z impurities (~ 50%) and W (~ 10%) in the discharges that followed powder injection. Along with the improved wall conditions, WEST discharges with B powder injection observed improved confinement, as the stored energy WMHD, neutron rate, and electron temperature Te increased significantly (10–25% for WMHD and 60–200% for the neutron rate) at constant input power. These increases in confinement scale up with the powder drop rate and are likely due to the suppression of ion temperature gradient (ITG) turbulence from changes in Zeff and/or modifications to the electron density profile.
Type:
Dataset
Issue Date:
2022

65. Nonlinear growth of magnetic islands by passing fast ions in NSTX

Author(s):
Yang, James; Fredrickson, Eric; Podestà, Mario; Poli, Francesca
Abstract:
The growth of magnetic islands in NSTX is modeled successfully, with the consideration of passing fast ions. It is shown that a good quantitative agreement between simulation and experimental measurement can be achieved when the uncompensated cross-field current induced by passing fast ions is included in the island growth model. The fast ion parameters, along with other equilibrium parameters, are obtained self-consistently using the TRANSP code with the assumptions of the ‘kick’ model (Podestà et al 2017 Plasma Phys. Control. Fusion 59 095008). The results show that fast ions can contribute to overcoming the stabilizing effect of polarization current for magnetic island growth.
Type:
Dataset
Issue Date:
2022

66. Streaked Sub-ps-resolution X-ray Line Shapes and Implications for Solid-density Plasma Dynamics

Author(s):
Kraus, B. Frances; Gao, Lan; Hill, K. W.; Bitter, M.; Efthimion, P. C.; Hollinger, R.; Wang, Shoujun; Song, Huanyu; Nedbailo, R.; Rocca, J. J.; Mancini, R. C.; MacDonald, M. J.; Beatty, C. B.; Shepherd, R.
Abstract:
A high-resolution x-ray spectrometer was coupled with an ultrafast x-ray streak camera to produce time-resolved line shape spectra measured from hot, solid-density plasmas. A Bragg crystal was placed near a laser-produced plasma to maximize throughput; alignment tolerances were established by raytracing. The streak camera produced single-shot time-resolved spectra, heavily sloped due to photon time-of-flight differences, with sufficient reproducibility to accumulate photon statistics. The images are time-calibrated by the slope of streaked spectra and dewarped to generate spectra emitted at different times defined at the source. The streaked spectra demonstrate the evolution of spectral shoulders and other features on ps timescales, showing the feasibility of plasma parameter measurements on the rapid timescales necessary to study high-energy-density plasmas.
Type:
Dataset
Issue Date:
2022

67. Supplemental material for: Verification, validation, and results of an approximate model for the stress of a Tokamak toroidal field coil at the inboard midplane

Author(s):
Swanson, CPS; Kahn, S; Rana, C; Titus, PH; Brooks, AW; Guttenfelder, W; Zhai, Y; Brown, TG; Menard, JE
Abstract:
This is the supplemental material for the manuscript "Verification, validation, and results of an approximate model for the stress of a Tokamak toroidal field coil at the inboard midplane" submitted to Fusion Engineering and Design. This material includes PDF writeups of the derivations of the axisymmetric extended plane strain model, the elastic properties smearing model, and 20+ MATLAB scripts and functions which implement the model and generate the figures in the paper.
Type:
collection, Dataset, and Software
Issue Date:
2022

69. Topological Langmuir-cyclotron wave

Author(s):
Qin, Hong; Fu, Yichen
Abstract:
The data set consists of the figures in a manuscript tilted Topological Langmuir-cyclotron wave. There are 10 figures with captions.
Type:
Image
Issue Date:
2022

70. CMT3D - Catalog

Author(s):
Sawade, Lucas
Abstract:
Catalog of Global CMTSOLUTIONs inverted using 3D Green functions that were computed with the adjoint tomography model GLAD-M25. The full methodology of the inversion procedure is described in the accompanying journal article of the same name.
Type:
Dataset
Issue Date:
22 December 2021