Toroidal ripple transport of beam ions in the mega-ampere spherical tokamak
- EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)
- Plasma Research Laboratory, Research School of Physical Science and Engineering, Australian National University, Canberra, ACT 0200 (Australia)
The transport of injected beam ions due to toroidal magnetic field ripple in the mega-ampere spherical tokamak (MAST) is quantified using a full orbit particle tracking code, with collisional slowing-down and pitch-angle scattering by electrons and bulk ions taken into account. It is shown that the level of ripple losses is generally rather low, although it depends sensitively on the major radius of the outer midplane plasma edge; for typical values of this parameter in MAST plasmas, the reduction in beam heating power due specifically to ripple transport is less than 1%, and the ripple contribution to beam ion diffusivity is of the order of 0.1 m{sup 2} s{sup -1} or less. It is concluded that ripple effects make only a small contribution to anomalous transport rates that have been invoked to account for measured neutron rates and plasma stored energies in some MAST discharges. Delayed (non-prompt) losses are shown to occur close to the outer midplane, suggesting that banana-drift diffusion is the most likely cause of the ripple-induced losses.
- OSTI ID:
- 22072577
- Journal Information:
- Physics of Plasmas, Vol. 19, Issue 7; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effects of toroidal field ripple on suprathermal ions in tokamak plasmas
The poloidal distribution of turbulent fluctuations in the Mega-Ampere Spherical Tokamak