Isotopic mass dependence of the transport of hydrogenic species in TFTR discharges
Conference
·
OSTI ID:489376
- Princeton Univ., NJ (United States)
In plasmas with deuterium-only neutral beam injection, the presence of tritium recycled from the walls, or puffed in as a gas can be detected by measuring the deuterium-tritium neutron emission profiles. The TRANSP plasma analysis code can be used to simulate these profiles. A single prescription for the tritium transport and recycling has been used to model deuterium- only neutral beam injection TFTR supershots, reversed shear (RS) and enhanced reversed shear (ERS) discharges, H-mode discharges, and L-mode discharges. Good agreements are achieved between simulated and measured quantities. TRANSP calculates the particle balance from measured quantities. The radial flux profile for the hydrogenic: species j can be modeled with explicit diffusivity and pinch profiles as {Tau}{sub j}(R,t) = - D{sub j} grad(n{sub j}) + V{sub j} n{sub j} The best agreement with neutron emission measurements is achieved with the following mass dependencies: (D {approximately} A{sup 0} and V {approximately} A{sup -1}). Alternative prescriptions have been tested. For instance, (D {approximately} A{sup 0} and V {approximately} A{sup 0}) or (D {approximately} A{sup 0} and V {approximately} A{sup -0.5}) or (D {approximately} A{sup -1} and V {approximately} A{sup 0}) are incompatible with neutron emission measurements. The effects of brief tritium gas puffs into discharges with deuterium-only neutral beam injection can also be modeled using the same prescription by changing the boundary conditions. The tritium ionization rate in the edge is increased during the puff. The results for D{sub j} and V{sub j} will be compared with measurements of He transport during He gas puffs, of tritium transport derived directly from the neutron emission during tritium gas puffs, and of deuterium transport in discharges with tritium-only neutral beam injection.
- DOE Contract Number:
- AC02-76CH03073
- OSTI ID:
- 489376
- Report Number(s):
- CONF-960354--
- Country of Publication:
- United States
- Language:
- English
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