Particle and energy transport studies on TFTR and implications for helium ash in future fusion devices
Local thermal particle and energy transport studies of balanced-injection L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power have been performed on TFTR. The particle transport of He{sup 2+} and electrons following a small helium gas puff and Fe{sup 24+} induced by laser ablation has been examined and compared to the local energy transport characteristics inferred from power balance analysis. All particle perturbation diffusivities are radially hollow and are similar in magnitude and shape to the effective thermal conductivities found by power balance analysis. All particle diffusivities are 1--2 orders of magnitude larger than neoclassical values, except near the magnetic axis. A reduction in the helium diffusivity D{sub He} in the Supershot as compared to the L-mode is accompanied by a similar reduction in the effective single fluid thermal conductivity {chi}fluid. Also, the helium core convective velocity V{sub He} is found to increase in the Supershot over the L-Mode for r/a < 0.5. A quasilinear model of electrostatic drift waves has been used to calculate ratios between particle and energy fluxes in the Supershot. The measured ratios of the helium and iron particle diffusivities are in good accord with predictions, as are predicted ratios of V{sub He}/D{sub He}. Modelling indicates that the similarity in magnitude and profile shape of D{sub He} and {chi}fluid has generally favorable implications for helium ash content in a future fusion reactor. The core convection found in the Supershot increases the helium concentration on axis but does not reduce the plasma reactivity significantly.
- Research Organization:
- Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 10145612
- Report Number(s):
- PPPL-2887; IAEA-CN-56/A-7-16; CONF-920913-27; ON: DE93011499
- Resource Relation:
- Conference: 14. international conference on plasma physics and controlled nuclear fusion research,Wurzburg (Germany),30 Sep - 7 Oct 1992; Other Information: PBD: Mar 1993
- Country of Publication:
- United States
- Language:
- English
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