TY - JOUR
T1 - Nondimensional transport scaling in the Tokamak Fusion Test Reactor
T2 - Is tokamak transport Bohm or gyro-Bohm?
AU - Perkins, F. W.
AU - Barnes, Cris W.
AU - Johnson, D. W.
AU - Scott, S. D.
AU - Zarnstorff, M. C.
AU - Bell, M. G.
AU - Bell, R. E.
AU - Bush, C. E.
AU - Grek, B.
AU - Hill, K. W.
AU - Mansfield, D. K.
AU - Park, H.
AU - Ramsey, A. T.
AU - Schivell, J.
AU - Stratton, B. C.
AU - Synakowski, E.
PY - 1993
Y1 - 1993
N2 - General plasma physics principles state that power flow Q(r) through a magnetic surface in a tokamak should scale as Q(r) = {32π2Rr 3Te2c nea/[eB(a2-r 2)2]} F(ρ*,β,v*,r/a,q,s,r/R,...) where the arguments of F are local, nondimensional plasma parameters and nondimensional gradients. This paper reports an experimental determination of how F varies with normalized gyroradius ρ* ≡ (2T eMi)1/2c/eBa and collisionality v* ≡ (R/r)3/2qRve(me/ 2Te) 1/2 for discharges prepared so that other nondimensional parameters remain close to constant. Tokamak Fusion Test Reactor (TFTR) [D. M. Meade et al., in Plasma Physics and Controlled Nuclear Fusion Research, 1990, Proceedings of the 13th International Conference, Washington (International Atomic Energy Agency, Vienna, 1991), Vol. 1, p. 9] L-mode data show F to be independent of ρ* and numerically small, corresponding to Bohm scaling with a small multiplicative constant. By contrast, most theories predict gyro-Bohm scaling: F ∝ ρ*. Bohm scaling implies that the largest scale size for microinstability turbulence depends on machine size. Analysis of a collisionality scan finds Bohm-normalized power flow to be independent of collisionality. Implications for future theory, experiment, and reactor extrapolations are discussed.
AB - General plasma physics principles state that power flow Q(r) through a magnetic surface in a tokamak should scale as Q(r) = {32π2Rr 3Te2c nea/[eB(a2-r 2)2]} F(ρ*,β,v*,r/a,q,s,r/R,...) where the arguments of F are local, nondimensional plasma parameters and nondimensional gradients. This paper reports an experimental determination of how F varies with normalized gyroradius ρ* ≡ (2T eMi)1/2c/eBa and collisionality v* ≡ (R/r)3/2qRve(me/ 2Te) 1/2 for discharges prepared so that other nondimensional parameters remain close to constant. Tokamak Fusion Test Reactor (TFTR) [D. M. Meade et al., in Plasma Physics and Controlled Nuclear Fusion Research, 1990, Proceedings of the 13th International Conference, Washington (International Atomic Energy Agency, Vienna, 1991), Vol. 1, p. 9] L-mode data show F to be independent of ρ* and numerically small, corresponding to Bohm scaling with a small multiplicative constant. By contrast, most theories predict gyro-Bohm scaling: F ∝ ρ*. Bohm scaling implies that the largest scale size for microinstability turbulence depends on machine size. Analysis of a collisionality scan finds Bohm-normalized power flow to be independent of collisionality. Implications for future theory, experiment, and reactor extrapolations are discussed.
UR - https://www.scopus.com/pages/publications/36449002459
UR - https://www.scopus.com/pages/publications/36449002459#tab=citedBy
U2 - 10.1063/1.860534
DO - 10.1063/1.860534
M3 - Article
AN - SCOPUS:36449002459
SN - 0899-8221
VL - 5
SP - 477
EP - 498
JO - Physics of Fluids B
JF - Physics of Fluids B
IS - 2
ER -