Results 31 to 40 of about 4,889,124 (198)

Meta variance reduction for Monte Carlo estimation of energetic particle confinement during stellarator optimization [PDF]

Journal of Computational Physics, 2023
This work introduces meta estimators that combine multiple multifidelity techniques based on control variates, importance sampling, and information reuse to yield a quasi-multiplicative amount of variance reduction.
F. Law, A. Cerfon, B. Peherstorfer, F. Wechsung   +3 more
semanticscholar   +1 more source

Optimizing Stellarators for Turbulent Transport [PDF]

Physical Review Letters, 2010
Up to now, the term "transport-optimized" stellarators has meant optimized to minimize neoclassical transport, while the task of also mitigating turbulent transport, usually the dominant transport channel in such designs, has not been addressed, due to the complexity of plasma turbulence in stellarators.
Mynick, H., Pomphrey, N., Xanthopoulos, P.   +2 more
openaire   +6 more sources

Coarse-grained gyrokinetics for the critical ion temperature gradient in stellarators

Physical Review Research, 2022
We present a modified gyrokinetic theory to predict the critical gradient that determines the linear onset of the ion temperature gradient (ITG) mode in stellarator plasmas.
G. T. Roberg-Clark, G. G. Plunk, P. Xanthopoulos   +2 more
doaj   +1 more source

Uncertainty quantification in three‐dimensional magnetohydrodynamic equilibrium reconstruction via surrogate‐assisted Bayesian inference

Contributions to Plasma Physics, Volume 63, Issue 5-6, June-July 2023., 2023
Abstract In three‐dimensional (3D) equilibrium, reconstruction defining parameters of an ideal magneto‐hydrodynamic equilibrium are inferred from a set of plasma diagnostic measurements. For the reconstructed parameters, various forms of uncertainty estimates exist within common 3D reconstruction frameworks.
Robert Köberl, Udo von Toussaint, Hans‐Joachim Bungartz, Jonathan Schilling, Christopher G. Albert, W7‐X Team   +5 more
wiley   +1 more source

Physics-regularized neural network of the ideal-MHD solution operator in Wendelstein 7-X configurations

Nuclear Fusion, 2023
The computational cost of constructing 3D magnetohydrodynamic (MHD) equilibria is one of the limiting factors in stellarator research and design. Although data-driven approaches have been proposed to provide fast 3D MHD equilibria, the accuracy with ...
Andrea Merlo, Daniel Böckenhoff, Jonathan Schilling, Samuel Aaron Lazerson, Thomas Sunn Pedersen, the W7-X Team   +5 more
doaj   +1 more source

Improving the stellarator through advances in plasma theory [PDF]

, 2022
Improvements to the stellarator concept can be realized through advancements in theoretical and computational plasma physics. Herein, recent advances are reported in the topical areas of: 1) improved energetic ion confinement, 2) the impact of three ...
Duff, J., Anderson, D., Kruger, T.G., Terry, P.W., Hegna, C., A. Bader, A. Ware, Anderson, D.T., Drevlak, M., McKinney, I., Bhattacharya, A., M.J. Pueschel, I.J. McKinney, Paul, E., Schmitt, J.S., Kruger, T., Faber, B., J.M. Duff, Ware, A.S., Zarnstorff, M.C., T. Bechtel, Bechtel, T.A., P.W. Terry, M.C. Zarnstorff, Landreman, M., Duff, J.M., Schmitt, J., C.C. Hegna, Bhattacharjee, A., Kotschenreuther, M., M. Drevlak, Zhu, C., Bader, A., Cole, M., Terry, P., D.T. Anderson, A. Bhattacharya, Pueschel, M.J., McKinney, I.J., Hudson, S., B.J. Faber, Zarnstorff, M., M. Landreman, Hudson, S.R., M. Kotschenreuther, M. Cole, T. Kruger, Pueschel, M., E. Paul, Hegna, C.C., Ware, A., Bechtel, T., S.R. Hudson, Faber, B.J., C. Zhu   +54 more
core   +1 more source

Reduction of electrostatic turbulence in a quasi-helically symmetric stellarator via critical gradient optimization [PDF]

Journal of Plasma Physics, 2022
We present a stellarator configuration optimized for a large threshold (‘critical gradient’) for the onset of the ion temperature gradient (ITG) driven mode, which achieves the largest critical gradient we have seen in any stellarator.
G. Roberg-Clark, P. Xanthopoulos, G. Plunk   +2 more
semanticscholar   +1 more source

Optimizing the HSX stellarator for microinstability by coil-current adjustments

Nuclear Fusion, 2023
The optimization of helically symmetric experiment (HSX) for reduced microinstability has been achieved by examining a large set of configurations within a neighborhood of the standard operating configuration.
M.J. Gerard, B. Geiger, M.J. Pueschel, A. Bader, C.C. Hegna, B.J. Faber, P.W. Terry, S.T.A. Kumar, J.C. Schmitt   +8 more
doaj   +1 more source

Direct stellarator coil optimization for nested magnetic surfaces with precise quasi-symmetry [PDF]

Physics of Plasmas, 2022
We present a robust optimization algorithm for the design of electromagnetic coils that generate vacuum magnetic fields with nested flux surfaces and precise quasi-symmetry.
A. Giuliani, F. Wechsung, A. Cerfon, M. Landreman, G. Stadler   +4 more
semanticscholar   +1 more source

Optimizing stellarators for large flows [PDF]

Plasma Physics and Controlled Fusion, 2014
Plasma flow is damped in stellarators because they are not intrinsically ambipolar, unlike tokamaks, in which the flux-surface averaged radial electric current vanishes for any value of the radial electric field. Only quasisymmetric stellarators are intrinsically ambipolar, but exact quasisymmetry is impossible to achieve in non-axisymmetric toroidal ...
Calvo, Iván, Parra, Felix I, Alonso, J Arturo, Velasco, José Luis   +3 more
openaire   +2 more sources