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(TH/P3-22) Selfconsistent RF Driven and Bootstrap Currents

Y. Peysson¹⁾, J. Decker²⁾, A. Bers²⁾, A.K. Ram^2)
 
1) Commissariat A l'Energie Atomique (CEA), Saint-Paul-lez-Durance, France
²⁾ Plasma Science and Fusion Center Massachusetts Institute of Technology, Cambridge, USA

Abstract.  This important problem selfconsistent calculations of the bootstrap current with RF, taking into account possible synergistic effects, is addressed for the case of lower hybrid (LH) and electron cyclotron (EC) current drive by numerically solving the electron drift kinetic equation. Calculations are performed using a new, fast, and fully implicit code which solves the 3-D relativistic Fokker-Planck equation with quasilinear diffusion. These calculations take into account the perturbations to the electron distribution due to radial drifts induced by magnetic field gradient and curvature. While the synergism between bootstrap and LH-driven current does not seem to exceed 15%, it can reach 30-40% with the EC-driven current for some plasma parameters. In addition, considerable current can be generated by judiciously using ECCD with the Okhawa effect. This is in contrast to the usual ECCD which tries to avoid it. A detailed analysis of the numerical results is presented using a simplified analytical model which incorporates the underlying physical processes.

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