The optimisation of neutral beams for ignition and burn control on Next Step reactorsFunded under: FP3-FUSION 11C
The purpose of this paper is to identify the neutral beam injection (NBI) parameters for a system on a Next Step reactor, optimised for ignition and burn control, rather than current drive. The ITER-EDA concept in its 1993 version (R(0) = 7.75 m, I(p) = 25 MA, B(T) = 6T, a = 2.8 m, k = 1.6) is used as the main model. The dependence of the minimum power to ignite ITER-EDA on beam energy, beam geometry and beam isotope species is investigated for a plasma which conforms to Rebut-Lallia-Watkins transport in time dependent simulations. It is found that deuterium beams with an energy of 400 keV or above, in a geometry with tangency radius (R(T)) of approximately half the major radius, are sufficient for efficient ignition. The beam simulation results are compared with simulations using an idealised heating scheme. Impurities, particle confinement, energy confinement and the H-mode threshold are found to influence the power required for ignition, but have little significance in the choice of beam energy and geometry. Considerations with respect to loss of fast particles led to the adoption of a beam geometry with values of R(T) about half those of R(0) (very similar to that of JET), rather than perpendicular injection. Finally it is shown that burn control using NBI is possible on ITER-EDA in sub-ignited regimes.
Bibliographic Reference: Report: JET-P(93)103 EN (1993)
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon. OX14 3EA (GB)
Record Number: 199410029 / Last updated on: 1994-11-28
Original language: en
Available languages: en