The Effect of Trapped Electrons on the Wave-Induced Current

Taguchi, Masayoshi

doi:10.1143/jpsj.52.2035

Cited by 45 publications

(39 citation statements)

References 11 publications

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“…(22) for Z = 1, Θ = 0.01 (T ≈ 5 keV), v 1 = 0.4c = 4p t /m, and v 2 = 0.7c = 7p t /m (the parallel refractive index satisfies 1.43 < n < 2.5). Using the numerical solution for f (p) and S(p), and the definitions (11) and (12), we obtain J = 3.74 × 10 −4 qnc, P = 1.28 × 10 −3 mnc 2 ν c , and J/P = 0.293 q/mcν c . This is to be compared with the result given by Eq.…”

Section: Numerical Resultsmentioning

confidence: 99%

Efficiency of current drive by fast waves

Karney

Fisch

1985

The Physics of Fluids

149

106

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Section: Numerical Resultsmentioning

confidence: 99%

Efficiency of current drive by fast waves

Karney

Fisch

1985

The Physics of Fluids

149

106

View full text Add to dashboard Cite

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“…Since ∇ · (j B/B) = 0, which follows directly from Eq. (2), j /B = j / B = j B / B 2 is a function of only the flux-surface label, the final expression for the current drive can be written as follows [6,7,16,23,24]:…”

Section: A General Definitionsmentioning

confidence: 99%

“…(In this limit, kinetic models with bounce-averaging are applicable.) This model, which is accepted as most relevant to ECCD calculations in toroidal plasmas [5][6][7][23][24][25][26][27], usually tends to underestimate the current drive efficiency as it neglects all effects due to (barely) trapped electrons. For this model, the drag over the trapped electrons is assumed to be equal to its upper "geometrical" limit.…”

Section: Introductionmentioning

confidence: 99%

Electron cyclotron current drive in low collisionality limit: On parallel momentum conservation

et al. 2011

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A comprehensive treatment of the models used in ray-and beam-tracing codes to calculate the electron cyclotron current drive (ECCD) by means of the adjoint technique, based on the adjoint properties of the collision and Vlasov operators appearing in the drift-kinetic equation, is presented. Particular attention is focused on carefully solving the adjoint drift-kinetic equation (generalized Spitzer problem) with parallel momentum conservation in the like-particle collisions. The formulation of the problem is valid for an arbitrary magnetic configuration. Only the limit of low collisionality is considered here, which is of relevance for high-temperature plasmas. It is shown that the accurate solution of the adjoint drift-kinetic equation with parallel momentum conservation significantly differs (apart from the supra-thermal electron portion) from that calculated in the high-speed-limit, which is most commonly used in the literature. For high-temperature plasmas with significant relativistic effects, the accuracy of the resulting numerical models is demonstrated by ray-tracing calculations and benchmark results are presented. It is found that the ECCD efficiency calculated for ITER with parallel momentum conservation significantly exceeds the predictions obtained with the high-speed-limit model.

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“…We have implicitly assumed that δ ~ ∆ < (m/M) 1/2 so an isotropic temperature equilibration term should enter Eq. (11). However, such a term only leads to an isotropic modification of f, so does not alter t π and is ignored.…”

Section: Ion Formulationmentioning

confidence: 99%

A drift ordered short mean free path description for magnetized plasma allowing strong spatial anisotropy

2004

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Short mean free path descriptions of magnetized plasmas have existed for almost 50 years so it is surprising to find that further modifications are necessary. The earliest work adopted an ordering in which the flow velocity was assumed to be comparable to the ion thermal speed. Later, less well known studies extended the short mean free path treatment to the normally more interesting drift ordering in which the pressure times the mean flow velocity is comparable to the diamagnetic heat flow. Such an ordering is required to properly retain the temperature gradient terms in the viscosity that arise from the gyrophase dependent and independent portions of the distribution function. Our treatment corrects the expressions for the parallel and perpendicular collisional ion viscosities found in these later treatments which used an approximate truncated polynomial expression for the distribution function and neglected the non-linear piece of the collision operator due to its bi-linear form. The modified parallel and perpendicular ion viscosities contain additional terms quadratic in the heat flux. In addition, we solve for the electron parallel and gyro-viscosities which were not considered by previous drift ordered treatments. As in all drift orderings we assume the collision frequency is small compared to the cyclotron frequency. However, we permit the perpendicular scale lengths to be much less than the parallel ones as is the case in many magnetic confinement applications. As a result, our description is valid for turbulent and collisional transport, and also allows stronger poloidal density and temperature variation in a tokamak than the standard Pfirsch-Schlüter ordering.

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The Effect of Trapped Electrons on the Wave-Induced Current

Cited by 45 publications

References 11 publications

Efficiency of current drive by fast waves

Efficiency of current drive by fast waves

Electron cyclotron current drive in low collisionality limit: On parallel momentum conservation

A drift ordered short mean free path description for magnetized plasma allowing strong spatial anisotropy

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