FAST plasma scenarios and equilibrium configurations

Abstract

In this paper we present the fusion advanced studies torus (FAST) plasma scenarios and equilibrium configurations, designed to reproduce the ITER ones (with scaled plasma current) and suitable to fulfil plasma conditions for integrated studies of plasma-wall interaction, burning plasma physics, ITER relevant operation problems and steady state scenarios. The attention is focused on FAST flexibility in terms of both performance and physics that can be investigated: operations are foreseen in a wide range of parameters from high performance H-mode (toroidal field, B T , up to 8.5 T; plasma current, I P , up to 8 MA) to advanced tokamak (AT) operation (I P = 3 MA) as well as full non-inductive current scenario (I P = 2 MA). The coupled heating power is provided with 30 MW delivered by an ion cyclotron resonance heating system (30-90 MHz), 6 MW by a lower hybrid system (3.7 or 5 GHz) for the long pulse AT scenario, 4 MW by an electron cyclotron resonant heating system (170 GHz − B T = 6 T) for MHD and localized electron heating control and, eventually, with 10 MW by a negative neutral ion beam (NNBI), which the ports are designed to accommodate. In the reference H-mode scenario FAST preserves (with respect to ITER) fast ion induced as well as turbulence fluctuation spectra, thus addressing the cross-scale couplings issue of micro-to meso-scale physics. The non-inductive scenario at I P = 2 MA is obtained with 60-70% of bootstrap current and the remaining by LHCD. Predictive simulations of the H-mode scenarios have been performed by means of the JETTO code, using a semi-empirical mixed Bohm/gyro-Bohm transport model. Plasma position and shape control studies are also presented for the reference scenario.

Poloidal field circuits sensitivity studies and shape control in FAST

“…FAST is designed to be a very flexible device able to reproduce, with scaled plasma current, the ITER scenarios and suitable to fulfill plasma conditions for integrated studies of plasma-wall interaction, burning plasma physics, ITER relevant operation problems and steady state scenarios [2]. A DEMO relevant scenario with minor radius down to ∼0.45 m (keeping fixed the major radius, i.e.…”

“…FAST plasma scenarios and equilibrium configurations have been designed to reproduce the ITER ones (with scaled plasma current) and suitable to fulfill plasma conditions for integrated studies of plasma-wall interaction, burning plasma physics, ITER relevant operation problems and steady state scenarios [2]. However, being an experimental machine it would be limiting not having a large flexibility in the plasma shape.…”

Simulations of the SOL plasma for FAST, a proposed ITER satellite tokamak

“…This first exploration of the SOL condition in FAST considers the reference scenario equilibrium [8] for some tentative cases for the divertor (D) geometry. These cases, listed in the following and sketched in Fig.…”

Requirements specification for the Neutral Beam Injector on FAST

“…FAST is being proposed as a European experiment in support to the operations on ITER and to the design of DEMO [1,2]. The specific mission of this relatively compact (R = 1.82 m, a = 0.64 m) device is an integrated approach to a number of outstanding burning plasmas physics and operational issues with an emphasis on the impact of fast particles on turbulent transport.…”

“…In this respect the inclusion of a Neutral Beam Injector to complement the ICRH, LH and ECRH systems is of particular relevance. The reference H-mode scenario in FAST features a single-null diverted, 6.5 MA of plasma current, 7.5 T of toroidal magnetic field and 30 MW of total input power [1,2], with a central electron density of about 2.5 × 10 20 m −3 . The main physics requirements for a beam on FAST have been investigated, and several simulations varying beam parameters (species, energy, geometry, divergence) have been performed by means of the NEMO/SPOT codes [3] simulating the interaction of the beam with the standard FAST H-mode plasma.…”