Stellarator transport optimization with self-consistent electric fields

Conference · Thu Sep 01 04:00:00 EDT 1994

OSTI ID:10183750

Lyon, J F; Painter, S L; Kovrizhnykh, L M; Gulec, K

Future large stellarators will operate in the low-collisionality regime where neoclassical helical-ripple-induced transport is an important, if not dominant, element in the transport. In this regime, E {times} B poloidal orbit rotation can drastically change the terms in the 1-D particle and heat flow equations. Usually, values for the electron and ion densities [n{sub e}({rho}) and N{sub i}({rho})] and the radial component of the electric field [E{sub r}({rho})] are assumed, and the 1-D heat flow equations are solved for the electron and ion temperatures [T{sub 0}({rho}) and T{sub i}({rho})]: here {rho} = r/a{sub p} is the normalized plasma radius. Previous studies assumed parabolic potential profiles (E{sub r} {proportional_to} {rho}) for different assumed profiles for n({rho}). Solutions with negative electric field led to a lower temperature and higher density than those with positive electric field, but required more initial hearing to reach ignition. No solutions were possible for some choices of parameters. In this paper, steady-state (1-D) integral-differential equations for the heat and particle fluxes for the ions (D,T) and electrons are solved for n{sub e}(r), n{sub i}(r), T{sub e}(r), T{sub i}(r), and E{sub r}(r). The electric field is determined from the ambipolarity condition. The electric field e enters both through an E/B drift term in the denominators of {chi} and D, and directly through the sign-dependent {del}{phi} term. The volumetric heat sources (and sinks) are the usual alpha-particle hearing, electron-ion heat transfer, and radiation terms. The form for the particle source rate (s) is chosen to represent shallow or deep fueling of the plasma.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 10183750
• Report Number(s): CONF-940635--16; ON: DE94019151
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700330
AMBIPOLAR DIFFUSION
CHARGED-PARTICLE TRANSPORT
ELECTRON DENSITY
ELECTRON TEMPERATURE
HEAT TRANSFER
NEOCLASSICAL TRANSPORT THEORY
ONE-DIMENSIONAL CALCULATIONS
PLASMA DRIFT
PLASMA KINETICS, TRANSPORT, AND IMPURITIES
STELLARATORS