Observation of particle transport barriers in reverse shear plasmas on the Tokamak Fusion Test Reactor

P. C. Efthimion; S. Von Goeler; W. A. Houlberg; E. J. Synakowski; M. C. Zarnstorff; S. H. Batha; R. E. Bell; M. Bitter; C. E. Bush; F. M. Levinton; E. Mazzucato; D. McCune; D. Mueller; H. Park; A. T. Ramsey; A. L. Roquemore; G. Taylor

doi:10.1063/1.872853

Observation of particle transport barriers in reverse shear plasmas on the Tokamak Fusion Test Reactor

P. C. Efthimion, S. Von Goeler, W. A. Houlberg, E. J. Synakowski, M. C. Zarnstorff, S. H. Batha, R. E. Bell, M. Bitter, C. E. Bush, F. M. Levinton, E. Mazzucato, D. McCune, D. Mueller, H. Park, A. T. Ramsey, A. L. Roquemore, G. Taylor

Department of Physics

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Abstract

Perturbative experiments on the Tokamak Fusion Test Reactor [Phys. Plasmas 4, 1736 (1997)] (TFTR) have investigated transport in reverse shear plasmas. On TFTR, reverse magnetic shear plasmas bifurcate into two states with different transport properties: reverse shear (RS) and enhanced reverse shear (ERS) with improved core confinement. Measurements of the 14 MeV t(d,n) α neutrons and charge-exchange recombination radiation spectra are used to infer the trace tritium and helium profiles, respectively. The profile evolution indicate the formation of core particle transport barriers in ERS plasmas. The transport barrier is manifested by an order-of-magnitude reduction in the particle diffusivity (D_T,D_He) and a smaller reduction in the pinch within the reverse shear region. The low diffusivities are consistent with neoclassical predictions. Furthermore, D_T and D_He ≈ χ_eff, the effective thermal diffusivity. Although the measured coefficients imply no helium ash accumulation, the situation is uncertain in a reactor due to unknown χ_eff scaling.

Original language	English
Pages (from-to)	1832-1838
Number of pages	7
Journal	Physics of Plasmas
Volume	5
Issue number	5 PART 1
DOIs	https://doi.org/10.1063/1.872853
State	Published - May 1998

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Efthimion, P. C., Von Goeler, S., Houlberg, W. A., Synakowski, E. J., Zarnstorff, M. C., Batha, S. H., Bell, R. E., Bitter, M., Bush, C. E., Levinton, F. M., Mazzucato, E., McCune, D., Mueller, D., Park, H., Ramsey, A. T., Roquemore, A. L., & Taylor, G. (1998). Observation of particle transport barriers in reverse shear plasmas on the Tokamak Fusion Test Reactor. Physics of Plasmas, 5(5 PART 1), 1832-1838. https://doi.org/10.1063/1.872853

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title = "Observation of particle transport barriers in reverse shear plasmas on the Tokamak Fusion Test Reactor",

abstract = "Perturbative experiments on the Tokamak Fusion Test Reactor [Phys. Plasmas 4, 1736 (1997)] (TFTR) have investigated transport in reverse shear plasmas. On TFTR, reverse magnetic shear plasmas bifurcate into two states with different transport properties: reverse shear (RS) and enhanced reverse shear (ERS) with improved core confinement. Measurements of the 14 MeV t(d,n) α neutrons and charge-exchange recombination radiation spectra are used to infer the trace tritium and helium profiles, respectively. The profile evolution indicate the formation of core particle transport barriers in ERS plasmas. The transport barrier is manifested by an order-of-magnitude reduction in the particle diffusivity (DT,DHe) and a smaller reduction in the pinch within the reverse shear region. The low diffusivities are consistent with neoclassical predictions. Furthermore, DT and DHe ≈ χeff, the effective thermal diffusivity. Although the measured coefficients imply no helium ash accumulation, the situation is uncertain in a reactor due to unknown χeff scaling.",

author = "Efthimion, {P. C.} and {Von Goeler}, S. and Houlberg, {W. A.} and Synakowski, {E. J.} and Zarnstorff, {M. C.} and Batha, {S. H.} and Bell, {R. E.} and M. Bitter and Bush, {C. E.} and Levinton, {F. M.} and E. Mazzucato and D. McCune and D. Mueller and H. Park and Ramsey, {A. T.} and Roquemore, {A. L.} and G. Taylor",

year = "1998",

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doi = "10.1063/1.872853",

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Efthimion, PC, Von Goeler, S, Houlberg, WA, Synakowski, EJ, Zarnstorff, MC, Batha, SH, Bell, RE, Bitter, M, Bush, CE, Levinton, FM, Mazzucato, E, McCune, D, Mueller, D, Park, H, Ramsey, AT, Roquemore, AL & Taylor, G 1998, 'Observation of particle transport barriers in reverse shear plasmas on the Tokamak Fusion Test Reactor', Physics of Plasmas, vol. 5, no. 5 PART 1, pp. 1832-1838. https://doi.org/10.1063/1.872853

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T1 - Observation of particle transport barriers in reverse shear plasmas on the Tokamak Fusion Test Reactor

AU - Efthimion, P. C.

AU - Von Goeler, S.

AU - Houlberg, W. A.

AU - Synakowski, E. J.

AU - Zarnstorff, M. C.

AU - Batha, S. H.

AU - Bell, R. E.

AU - Bitter, M.

AU - Bush, C. E.

AU - Levinton, F. M.

AU - Mazzucato, E.

AU - McCune, D.

AU - Mueller, D.

AU - Park, H.

AU - Ramsey, A. T.

AU - Roquemore, A. L.

AU - Taylor, G.

PY - 1998/5

Y1 - 1998/5

N2 - Perturbative experiments on the Tokamak Fusion Test Reactor [Phys. Plasmas 4, 1736 (1997)] (TFTR) have investigated transport in reverse shear plasmas. On TFTR, reverse magnetic shear plasmas bifurcate into two states with different transport properties: reverse shear (RS) and enhanced reverse shear (ERS) with improved core confinement. Measurements of the 14 MeV t(d,n) α neutrons and charge-exchange recombination radiation spectra are used to infer the trace tritium and helium profiles, respectively. The profile evolution indicate the formation of core particle transport barriers in ERS plasmas. The transport barrier is manifested by an order-of-magnitude reduction in the particle diffusivity (DT,DHe) and a smaller reduction in the pinch within the reverse shear region. The low diffusivities are consistent with neoclassical predictions. Furthermore, DT and DHe ≈ χeff, the effective thermal diffusivity. Although the measured coefficients imply no helium ash accumulation, the situation is uncertain in a reactor due to unknown χeff scaling.

AB - Perturbative experiments on the Tokamak Fusion Test Reactor [Phys. Plasmas 4, 1736 (1997)] (TFTR) have investigated transport in reverse shear plasmas. On TFTR, reverse magnetic shear plasmas bifurcate into two states with different transport properties: reverse shear (RS) and enhanced reverse shear (ERS) with improved core confinement. Measurements of the 14 MeV t(d,n) α neutrons and charge-exchange recombination radiation spectra are used to infer the trace tritium and helium profiles, respectively. The profile evolution indicate the formation of core particle transport barriers in ERS plasmas. The transport barrier is manifested by an order-of-magnitude reduction in the particle diffusivity (DT,DHe) and a smaller reduction in the pinch within the reverse shear region. The low diffusivities are consistent with neoclassical predictions. Furthermore, DT and DHe ≈ χeff, the effective thermal diffusivity. Although the measured coefficients imply no helium ash accumulation, the situation is uncertain in a reactor due to unknown χeff scaling.

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JO - Physics of Plasmas

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Observation of particle transport barriers in reverse shear plasmas on the Tokamak Fusion Test Reactor

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