Beam-Ion Transport in Tokamaks: Thermalization in Large Orbit-Width Regime

"Comparison with the present results shows that the small orbit-width approximation introduces $\ge$5% errors in the density, parallel momentum, and energy moments when \rho\sb{θ}/L = 0.86 in low-$Z\sb{\rm eff}$ plasmas. These results are observed for all source pitch-angles studied except the deeply passing sources, which are in good agreement ($\le$5%) with the small orbit-width model. A non-zero current, due to the large orbit-width of the trapped fast ions, is identified and related to, the superthermal alpha particle bootstrap ""seed"" current. In low-$Z\sb{\rm eff}$ plasmas, pitch-angle scattering is only important for marginally passing ion sources. Scattering into the trapping region causes substantial inward-directed transport that is not predicted in the convective model. Parallel momentum is reduced by $\sim$70%. For cases with marginally passing sources in higher $Z\sb{\rm eff}$ plasmas, transport into the trapping region scales linearly with scattering frequency $\nu\sb{\perp}.$ The results are sensitive to source localization in a layer at the trapping/passing boundary. Significant broadening of profiles is observed for cases with deeply trapped sources in higher $Z\sb{\rm eff}$ plasmas."

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Nuclear Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Sager, Glenn Terry

Contributors dc:contributor

• George Hunter Miley

• Engineering, Nuclear

Language dc:language

eng

Identifier

(MiAaPQ)AAI9904576

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85942