Heating and Current Drive Requirements towards Steady State Operation in ITER
Authors: F.M. Poli, P.T. Bonoli, C.E. Kessel, D.B. Batchelor, M. Gorelenkova, B. Harvey and Y. Petrov
Abstract:
Steady state scenarios envisaged for ITER aim at optimizing the bootstrap current, while maintaining sufficient
confinement and stability to provide the necessary fusion yield. Non-inductive scenarios will need to operate with Internal
Transport Barriers (ITBs) in order to reach adequate fusion gain at typical currents of 9 MA. However, the large pressure
gradients associated with ITBs in regions of weak or negative magnetic shear can be conducive to ideal MHD instabilities,
reducing the no-wall limit. The E x B flow shear from toroidal plasma rotation is expected to be low in ITER, with a major
role in the ITB dynamics being played by magnetic geometry. Combinations of H/CD sources that maintain reverse or weak
magnetic shear profiles throughout the discharge are the focus of this work. Time-dependent transport simulations indicate
that, with a trade-off of the EC equatorial and upper launcher, the formation and sustainment of quasi-steady state ITBs could
be demonstrated in ITER with the baseline heating configuration. However, with proper constraints from peeling-ballooning
theory on the pedestal width and height, the fusion gain and the maximum non-inductive current are below the ITER target.
Upgrades of the heating and current drive system in ITER, like the use of Lower Hybrid current drive, could overcome these limitations, sustaining higher non-inductive current and confinement, more expanded ITBs which are ideal MHD stable.
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Submitted to: 20th Topical Conference on Radio Frequency Power in Plasmas, Sorrento, Italy, June 25-28, 2013
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Download PPPL-4907 (pdf 485 KB 8 pp)
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