Simulations of Non-Inductive Current Ramp Up and Sustainment in the National Spherical Torus Experiment Upgrade
Authors: F. M. Poli, R.G. Andre, N. Bertelli, S.P. Gerhardt, D. Mueller, G. Taylor
Abstract: The start-up, ramp-up, and sustainment of a
tokamak plasma utilizing little to no induction from a central
solenoid is a major challenge in magnetic fusion. Future
Fusion Nuclear Science Facilities based on the Spherical Tokamak
design are projected to rely on Neutral Beam Injection to sustain
about half of the plasma current in steady-state, with the
remainder provided by the self-generated bootstrap current, and to
provide heating and current drive for non-inductive current
ramp-up. This work discusses predictive simulations of
non-inductive ramp-up and sustainment on the National Spherical
Torus Experiment Upgrade. Radio-Frequency waves at harmonics
higher than the ion cyclotron resonance (HHFW) and Neutral Beam
Injection are combined to ramp the plasma current non-inductively.
Simulations indicate that density feedback control and current
pro file control will be necessary in order to attain the desired
target. It is shown that the addition of Electron Cyclotron wave
heating can signi ficantly increase the e ffectiveness of the
radio-frequency power and relax the requirements on the total
level of power that needs to be coupled to the startup plasma.
_________________________________________________________________________________________________
Submitted to: Nuclear Fusion
_________________________________________________________________________________________________
Download PPPL-5125 (pdf 2.7 MB 23 pp)
_________________________________________________________________________________________________