Charge exchange recombination spectroscopy measurements in the extreme ultraviolet region of central carbon concentrations during high power neutral beam heating in TFTR (Tokamak Fusion Test Reactor)

Technical Report · Fri Sep 01 00:00:00 EDT 1989

DOI:https://doi.org/10.2172/5577853· OSTI ID:5577853

Stratton, B C; Fonck, R J; Ramsey, A T; Synakowski, E J; Grek, B; Hill, K W; Johnson, D W; Mansfield, D K; Park, H; Taylor, G; Valanju, P M ^[1]

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1. Princeton Univ., NJ (USA). Plasma Physics Lab.

The carbon concentration in the central region of TFTR discharges with high power neutral beam heating has been measured by charge-extracted recombination spectroscopy (CXRS) of the C{sup +5} n = 3--4 transition in the extreme ultraviolet region. The carbon concentrations were deduced from absolute measurements of the line brightness using a calculation of the beam attenuation and the appropriate cascade-corrected line excitation rates. As a result of the high ion temperatures in most of the discharges, the contribution of beam halo neutrals to the line brightness was significant and therefore had to be included in the modeling of the data. Carbon concentrations have been measured in discharges with I{sub p} = 1.0-1.6 MA and beam power in the range of 2.6-30 MW, including a number of supershots. The results are in good agreement with carbon concentrations deduced from the visible bremsstrahlung Z{sub eff} and metallic impurity concentrations measured by x-ray pulse-height analysis, demonstrating the reliability of the atomic rates used in the beam attenuation and line excitation calculations. Carbon is the dominant impurity species in these discharges; the oxygen concentration measured via CXRS in a high beam power case was 0.0006 of n{sub e}, compard to 0.04 for carbon. Trends with I{sub p} and beam power in the carbon concentration and the inferred deuteron concentration are presented. The carbon concentration is independent of I{sub p} and decreases from 0.13 at 2.6 MW beam power to 0.04 at 30 MW, while the deuteron concentration increases from 0.25 to 0.75 over the same range of beam power. These changes are primarily the result of beam particle fueling, as the carbon density did not vary significantly with beam power. The time evolutions of the carbon and deuteron concentrations during two high power beam pulses, one which exhibited a carbon bloom and one which did not, are compared. 30 refs., 12 figs., 2 tabs.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5577853
• Report Number(s): PPPL-2648; ON: DE90000851; TRN: 89-024399
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
IMPURITIES
SPECTROSCOPY
TFTR TOKAMAK
BEAM INJECTION HEATING
CARBON IONS
CHARGE EXCHANGE
EXPERIMENTAL DATA
PLASMA DIAGNOSTICS
RECOMBINATION
CHARGED PARTICLES
DATA
HEATING
INFORMATION
IONS
NUMERICAL DATA
PLASMA HEATING
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
700101* - Fusion Energy- Plasma Research- Confinement
Heating
& Production
700103 - Fusion Energy- Plasma Research- Kinetics