Effects of energetic particle phase space modifications by instabilities on integrated modeling
Abstract
Tokamak plasmas can feature a large population of energetic particles (EP) from neutral beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, neutral beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effective tool for long timescale integrated simulations of tokamak plasmas, possibly including the effects of instabilities on EP dynamics. Available models differ in how EP distribution properties are modified by instabilities, e.g. in terms of gradients in real or phase space. It is therefore crucial to assess to what extent different assumptions in the transport models affect predicted quantities such as EP profile, energy distribution, NB driven current and energy/momentum transfer to the thermal populations. A newly developed kick model, which includes modifications of the EP distribution by instabilities in both real and velocity space, is used in this work tomore »
 Authors:
 Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
 Publication Date:
 Research Org.:
 Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC24)
 OSTI Identifier:
 1346925
 Grant/Contract Number:
 AC0209CH11466; FC0204ER54698
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Nuclear Fusion
 Additional Journal Information:
 Journal Volume: 56; Journal Issue: 11; Journal ID: ISSN 00295515
 Publisher:
 IOP Science
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Citation Formats
Podesta, M., Gorelenkova, M., Fredrickson, E. D., Gorelenkov, N. N., and White, R. B. Effects of energetic particle phase space modifications by instabilities on integrated modeling. United States: N. p., 2016.
Web. doi:10.1088/00295515/56/11/112005.
Podesta, M., Gorelenkova, M., Fredrickson, E. D., Gorelenkov, N. N., & White, R. B. Effects of energetic particle phase space modifications by instabilities on integrated modeling. United States. doi:10.1088/00295515/56/11/112005.
Podesta, M., Gorelenkova, M., Fredrickson, E. D., Gorelenkov, N. N., and White, R. B. 2016.
"Effects of energetic particle phase space modifications by instabilities on integrated modeling". United States.
doi:10.1088/00295515/56/11/112005. https://www.osti.gov/servlets/purl/1346925.
@article{osti_1346925,
title = {Effects of energetic particle phase space modifications by instabilities on integrated modeling},
author = {Podesta, M. and Gorelenkova, M. and Fredrickson, E. D. and Gorelenkov, N. N. and White, R. B.},
abstractNote = {Tokamak plasmas can feature a large population of energetic particles (EP) from neutral beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, neutral beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effective tool for long timescale integrated simulations of tokamak plasmas, possibly including the effects of instabilities on EP dynamics. Available models differ in how EP distribution properties are modified by instabilities, e.g. in terms of gradients in real or phase space. It is therefore crucial to assess to what extent different assumptions in the transport models affect predicted quantities such as EP profile, energy distribution, NB driven current and energy/momentum transfer to the thermal populations. A newly developed kick model, which includes modifications of the EP distribution by instabilities in both real and velocity space, is used in this work to investigate these issues. Coupled to TRANSP simulations, the kick model is used to analyze NBheated NSTX and DIIID discharges featuring unstable Alfvén eigenmodes (AEs). Results show that instabilities can strongly affect the EP distribution function, and modifications propagate to macroscopic quantities such as NBdriven current profile and NB power transferred to the thermal plasma species. Furthermore, those important aspects are only qualitatively captured by simpler fast ion transport models that are based on radial diffusion of energetic ions only.},
doi = {10.1088/00295515/56/11/112005},
journal = {Nuclear Fusion},
number = 11,
volume = 56,
place = {United States},
year = 2016,
month = 7
}

Effects of energetic particle phase space modifications by instabilities on integrated modeling
Tokamak plasmas can feature a large population of energetic particles (EP) from neutral beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, neutral beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effectivemore » 
Effects of energetic particle phase space modifications by instabilities on integrated modeling
Tokamak plasmas can feature a large population of energetic particles (EP) from Neutral Beam injection or fusion reactions. In turn, energetic particles can drive instabilities, which affect the driving EP population leading to a distortion of the original EP distribution function and of quantities that depend on it. The latter include, for example, Neutral Beam (NB) current drive and plasma heating through EP thermalization. Those effects must be taken into account to enable reliable and quantitative simulations of discharges for present devices as well as predictions for future burning plasmas. Reduced models for EP transport are emerging as an effectivemore » 
Alphaparticle losses from toroidicityinduced Alfven eigenmodes. Part I: Phasespace topology of energetic particle orbits in tokamak plasma
Phasespace topology of energetic particles in tokamak plasma with arbitrary shape of cross section is studied based upon the guiding center theory. Important phasespace boundaries such as prompt loss boundary, trapped passing boundary, and other boundaries between classes of nonstandard orbits (e.g., pinch and stagnation orbits) are studied. This phasespace topology information is applied to the study of anomalous phasespace diffusion due to finite amplitude Alfven wave fluctuations of energetic particles. The separatrix between trapped and circulating particles contributes dominantly to the losses. 
Kinetic theory of phase space plateaux in a nonthermal energetic particle distribution
The transformation of kinetically unstable plasma eigenmodes into holeclump pairs with temporally evolving carrier frequencies was recently attributed to the emergence of an intermediate stage in the mode evolution cycle, that of an unmodulated plateau in the phase space distribution of fast particles. The role of the plateau as the holeclump breeding ground is further substantiated in this article via consideration of its linear and nonlinear stability in the presence of fast particle collisions and sources, which are known to affect the production rates and subsequent frequency sweeping of holes and clumps. In particular, collisional relaxation, as mediated by e.g.more »