High-Q plasmas in the TFTR tokamak

Conference · Wed May 01 04:00:00 EDT 1991

OSTI ID:5830939

Jassby, D L; Bell, M G; Bitter, M; Boivin, R; Bretz, N L; Budny, R V; Dylla, H F; Efthimion, P C; Fredrickson, E D; Hawryluk, R J; Hill, K W; Hosea, J; Hsuan, H; Janos, A C; Jobes, F C; Johnson, D W; Johnson, L C; Kamperschroer, J; Kieras-Phillips, C; Kilpatrick, S J ; LaMarche, P H; LeBlanc, B; Mansfield, D K; McCune, D C; McGuire, K M; Meade, D M; Medley, S S; Mikkelsen, D R; Mueller, D; Owens, D

In the Tokamak Fusion Test Reactor, the highest neutron source strength S{sub n} and D-D fusion power gain Q{sub DD} are realized in the neutral-beam fueled and heated supershot'' regime that occurs after extensive wall conditioning to minimize recycling. For the best supershots, S{sub n} increases approximately as P{sub b}{sup 1.8}. The highest-Q shots are characterized by high T{sub e}, T{sub i}, and stored energy highly peaked density profiles, broad T{sub e} profiles, and lower Z{sub eff}. Replacement of critical areas of the graphite limiter tiles with carbon-fiber composite tiles, and improved alignment with the plasma, have mitigated the carbon bloom.'' Wall conditioning by lithium pellet injection prior to the beam pulse reduces carbon influx and particle recycling. Empirically, Q{sub DD} increases with decreasing pre-injection carbon radiation, and increases strongly with density peakedness during the beam pulse. To date the best fusion results are S{sub n} = 5 {times} 10{sup 16} n/s, Q{sub DD} = 1.85 {times} 10{sup {minus}3}, and neutron yield = 4.0 {times} 10{sup 16} n/pulse, obtained at I{sub p} = 1.6 to 1.9 MA and beam energy E{sub b} = 95 to 103 keV, with nearly balanced co- and counter-injected beam power. Computer simulations of supershot plasmas show that typically 50--60% of S{sub n} arises from beam-target reactions, with the remainder divided between beam-beam and thermonuclear reactions, the thermonuclear fraction increasing with P{sub b}. The simulations predict that Q{sub DT} = 0.3 to 0.4 would be obtained for the best present plasma conditions, if half the deuterium neutral beams were to be replaced by tritium beams. Somewhat higher values are calculated if D beams are injected into a predominantly tritium target plasma. The projected central beta of fusion alphas is 0.4--0.6%, a level sufficient for the study of alpha-induced collective effects. 16 refs., 8 figs., 3 tabs.

• Research Organization: Princeton Univ., NJ (USA). Plasma Physics Lab.
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5830939
• Report Number(s): PPPL-2756; CONF-9011127--19; ON: DE91012312
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
700102 -- Fusion Energy-- Plasma Research-- Diagnostics
700201 -- Fusion Power Plant Technology-- Blanket Engineering
CARBON
COMPUTERIZED SIMULATION
CONFINEMENT
ELEMENTAL MINERALS
ELEMENTS
EMISSION
FIRST WALL
GRAPHITE
LIMITERS
MEASURING INSTRUMENTS
MINERALS
NEUTRON DETECTORS
NEUTRON EMISSION
NONMETALS
PELLET INJECTION
PERFORMANCE
PLASMA CONFINEMENT
RADIATION DETECTORS
SIMULATION
TFTR TOKAMAK
THERMONUCLEAR REACTOR WALLS
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS