Collaboration with NSTX in Calculations of Radiofrequency and Neutral Beam Heating and Current Drive
Abstract
The overall objective of this project was to advance the understanding of heating and current drive necessary for toroidal magnetic confinement fusion energy reactors, and to provide accurate models for these sources to aid in understanding magnetohydrodynamic, transport and boundary physics issues. Increased understanding is provided by computer simulation using the underlying physics laws, and will lead to greater reliability and increased efficiency of a power producing fusion reactor. The proposed work entailed applications of existing CompX FokkerPlanck, ray tracing, fullwave microwave, and particle diffusion calculator codes to the National Spherical Torus Experiment at Princeton Plasma Physics Laboratory. Special features of NSTX include that large ion orbits are emphasized in its geometry and thus offer a major opportunity within fusion research for focused exploration of their ubiquitous effects, including comparison with simulation codes. The CompX CQL3D FokkerPlanck code was be further adapted to the finiteorbitwidth physics. Comparison with experiment ensured that the computer codes have sufficient accuracy to accurately model the experiments. Nonthermal distributions of energetic ions are produced in experiments and modeled with the codes exhibiting the signatures of auxiliary heating, transport, and radiation processes within the plasma. Using physicsbased modeling, in conjunction with experimental data, nonthermal distributions canmore »
 Authors:

 CompX, Del Mar, CA (United States)
 Publication Date:
 Research Org.:
 CompX, Del Mar, CA (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC), Fusion Energy Sciences (FES)
 Contributing Org.:
 Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
 OSTI Identifier:
 1574468
 Report Number(s):
 DOECompX66140
TRN: US2100345
 DOE Contract Number:
 SC0006614
 Resource Type:
 Technical Report
 Resource Relation:
 Related Information: PETROV, Yu.V., HARVEY, R.W., “A FullyNeoclassical FiniteOrbitWidth Version of the CQL3D FokkerPlanck Code”, Plasma Phys. Control. Fusion 58 (2016) 115001 (20 pages).doi:10.1088/07413335/58/11/115001Harvey, R.W. Petrov, Yu Liu, D. Heidbrink, W. Taylor, Gary Bonoli, P., “Temporal Dynamics of NSTX NBI+HHFW Discharges using CQL3DHybridFOW” AIP Conference Proceedings: 20th Topical Conference on Radio Frequency Power in Plasmas, at Sorrento, Italy, Volume: 1580, (2014). http://dx.doi.org/10.1063/1.4864551
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Citation Formats
Harvey, R. W.. Collaboration with NSTX in Calculations of Radiofrequency and Neutral Beam Heating and Current Drive. United States: N. p., 2019.
Web. doi:10.2172/1574468.
Harvey, R. W.. Collaboration with NSTX in Calculations of Radiofrequency and Neutral Beam Heating and Current Drive. United States. https://doi.org/10.2172/1574468
Harvey, R. W.. Thu .
"Collaboration with NSTX in Calculations of Radiofrequency and Neutral Beam Heating and Current Drive". United States. https://doi.org/10.2172/1574468. https://www.osti.gov/servlets/purl/1574468.
@article{osti_1574468,
title = {Collaboration with NSTX in Calculations of Radiofrequency and Neutral Beam Heating and Current Drive},
author = {Harvey, R. W.},
abstractNote = {The overall objective of this project was to advance the understanding of heating and current drive necessary for toroidal magnetic confinement fusion energy reactors, and to provide accurate models for these sources to aid in understanding magnetohydrodynamic, transport and boundary physics issues. Increased understanding is provided by computer simulation using the underlying physics laws, and will lead to greater reliability and increased efficiency of a power producing fusion reactor. The proposed work entailed applications of existing CompX FokkerPlanck, ray tracing, fullwave microwave, and particle diffusion calculator codes to the National Spherical Torus Experiment at Princeton Plasma Physics Laboratory. Special features of NSTX include that large ion orbits are emphasized in its geometry and thus offer a major opportunity within fusion research for focused exploration of their ubiquitous effects, including comparison with simulation codes. The CompX CQL3D FokkerPlanck code was be further adapted to the finiteorbitwidth physics. Comparison with experiment ensured that the computer codes have sufficient accuracy to accurately model the experiments. Nonthermal distributions of energetic ions are produced in experiments and modeled with the codes exhibiting the signatures of auxiliary heating, transport, and radiation processes within the plasma. Using physicsbased modeling, in conjunction with experimental data, nonthermal distributions can provide keys to validation and quantification of auxiliary heating physics. Nonthermal distributions also hold particular information on radial transport processes, not obscured by the smoothing Maxwellization effects of Coulomb collisions. Generally, radial transport is not well understood but is a key to efficient fusion energy production. By comparison with FokkerPlanck modeling, the velocity dependence of radial transport coefficients becomes experimentally accessible, particularly in cases of wellmodeled sources such as neutral beams, fast wave power, or the toroidal electric field. It is clear from modeling of fastwave interactions with ions that finiteorbitwidth effects play a significant role. For example, a different set of ions is computed to intersect a given cyclotron resonance depending on whether or not radial orbit drifts are taken into account. Also, radial transport, associated bootstrap current, and alpha channeling depend on radial drifts. Ion cyclotron heating above the first harmonic interacts preferentially with higher velocity ions, giving large radial drifts. The CQL3D FokkerPlanck code, maintained by the proposers, is a physics based model used extensively within the US fusion community to compare with and interpret experimental observations. At the beginning of this grant, bounceaverages of the rf quasilinear and other operators have been performed neglecting the radial drifts which give finite orbit widths to the particle orbits. The proposed work included a major upgrade to CQL3D to include finiteorbitwidth effects be accounted for by performing the bounceaverages of rf and neutral beam fast ions along guiding center orbits. This CQL3D enhancement provided microwave and neutral beam contributions to neoclassical radial transport coefficients for nonthermal distributions, and substantially increased the comprehensiveness of the ion model. Additional work validated FokkerPlanck and ray tracing modeling of neutral beam and high harmonic fast wave absorption and current drive against the NSTX experiment, as had been very successful for electron cyclotron current drive in the DIIID tokamak at General Atomics and lower hybrid waves on CMod at MIT. The validation work was in conjunction with staff and graduate students at Princeton Plasma Physics Laboratory. This DOE grant supported fusion energy research, a potential longterm solution to the world's energy needs. The research grant under consideration, DESC0006614, provided research support at the 0.3 FullTimeEquivalent level for application of computer models to aid in understanding and projecting efficacy of heating and current drive sources in the National Spherical Torus Experiment, a tokamak variant, at the Princeton Plasma Physics Laboratory. The NSTX experiment explores the physics of very tight aspect ratio, almost spherical tokamaks, aiming at producing steadystate fusion plasmas. The current drive is an integral part of the steadystate concept, maintaining the magnetic geometry in the steadystate tokamak.},
doi = {10.2172/1574468},
url = {https://www.osti.gov/biblio/1574468},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {11}
}