Assessment of operational space for long-pulse scenarios in ITER

Abstract

The operational space (I p − n) for long-pulse scenarios ( t burn ∼ 1000 s, Q 5) of ITER has been assessed by 1.5D core transport modelling with pedestal parameters predicted by the EPED1 code by a set of transport codes under a joint activity carried out by the Integrated Operational Scenario ITPA group. The analyses include the majority of transport models (CDBM, GLF23, Bohm/gyroBohm (BgB), MMM7.1, MMM95, Weiland, scaling-based) presently used for interpretation of experiments and ITER predictions. The EPED1 code was modified to take into account boundary conditions predicted by SOLPS4 for ITER. In contrast to standard EPED1 assumptions, EPED1 with the SOLPS boundary conditions predicts no degradation of the pedestal pressure as density is reduced. Lowering the plasma density to n e ∼ (5-6) × 10 19 m −3 leads to an increased plasma temperature (similar pedestal pressure), which reduces the loop voltage and increases the duration of the burn phase to t burn ∼ 1000 s with Q 5 for I p 13 MA at moderate normalized pressure (β N ∼ 2). These ITER plasmas require the same level of additional heating power as the reference Q = 10 inductive scenario at 15 MA (33 MW NBI and 17-20 MW EC heating and current drive power). However, unlike the 'hybrid' scenarios considered previously, these H-mode plasmas do not require specially shaped q profiles nor improved confinement in the core for the transport models considered in this study. Thus, these medium density H-mode plasma scenarios with I p 13 MA present an attractive alternative to hybrid scenarios to achieve ITER's long-pulse Q 5 scenario and deserve further analysis and experimental demonstration in present tokamaks.

Integrated core-SOL modelling of fuelling, density control and divertor heat loads for the flat-top phase of the ITER H-mode D-T plasma scenarios

“…Indeed, more recent simulations with ASTRA including the self-consistent evaluation of the pedestal pressure from the EPED1 model and the SOL relations derived from B2-EIRENE in [17] found similar values of Q for the densities modelled with JINTRAC [22]. In addition, the SOL parameter relation for the maximum power density at the target plates (including power deposited by radiation and neutral interaction) given in equations 1 and 4 in [17] seems to apply quite well also to the cases considered here.…”

Integrated simulations of H-mode operation in ITER including core fuelling, divertor detachment and ELM control

“…The analysis carried out by the application of then ELM energy density scaling in [4] together with the pedestal plasma pressure derived from EPED1+SOLPS predictions [5] indicates that ELM control to avoid melting of the inner W divertor monoblock top surface would not be required in ITER for 2.65T operation with q 95 ≥ 3 and ! "# / !"…”

Systematic linear-stability assessment of Alfvén eigenmodes in the presence of fusion α-particles for ITER-like equilibria

“…The results presented and discussed below were obtained for the ITER baseline scenario [8], with total plasma current I p = 15 MA, low shear safety-factor in the core region and q(0) = 0.987, peaked temperature profiles with T i (0) = 21.5 KeV for the DT ions and T e (0) = 24.7 KeV for the electrons, and flat density profiles (almost up to the edge) with n e (0) = 11 × 10 −19 m −3 and n i (0) = 8.6 × 10 −19 m −3 (FIG. 1).…”