DOI: 10.14457/tu.the.2017.213
title: Predictive simulation of demo performance using BALDUR integrated predictive modeling code

description: Self-consistent simulations of four DEMO designs have been carried out using the BALDUR integrated predictive modeling code in which theory-based models are used for core transport and boundary conditions. The four designs of DEMOs include the conceptual designs proposed by India, China, Europe, and Korea. It has been found that, with the exclusion of ELMs, the fusion gain (Qfusion) for these configurations at their design parameters ranges from 5 to 30, which are significantly lower than their estimations by the design teams, except the European design. It is also found that increasing of the auxiliary heating power and the electron line average density has positive impacts on the fusion performance, which could be used to enhance the performance to the design values. By increasing the auxiliary heating power by a factor of two, the increased fusion power ranges from 10% to 23%. In addition, increases of the line average electron density by a factor of two leads to significant improvement in fusion power ranging from 50% to 250%. Increase of impurity's atomic mass, however, lowers the fusion performance. In addition, model for the sawtooth triggering mechanisms (Porcelli et al 1996 Plasma Phys. Controlled FusionRef. code: 25605722040234ZTViv38, 2163) are used together with the modified version of the Kadomtsev sawtooth magnetic reconnection model (Kadomtsev 1975 Sov. J. Plasma Phys. 1, 389) to predict impacts of sawtooth oscillations on four conceptual DEMO designs in the BALDUR integrated predictive modelling code where theory-based models are used for core transport and boundary conditions. The four DEMO designs are proposed by teams from Europe, India, Chinese, and Korea. In this work, the plasma behavior is investigated during each sawtooth cycle as well as the comparison of plasma parameters for the simulations with and without sawtooth oscillation effects is analyzed. It is found that for all designs, sawtooth crashes are mostly triggered by the fast ion stabilization criterion. For sawtooth mixing region, for all designs, the sawtooth mixing radius depends mainly on the structure of pre-crash helical flux; the mixing radius based on European design tends to be the largest due to the largest expansion of pre-crash helical flux. In addition, for all designs, in the central core area, sawtooth oscillations lead to the plasma temperature which depends mainly on how large the mixing region is. However, for hollow density profiles with the exclusion of sawtooth effects, the presence of sawteeth results in a penetration of the electron density up to the magnetic axis for all designs except China in different degrees, depending on the characteristics of the electron density profile within the sawtooth mixing region. Moreover, for the low-charge impurities for the simulation based on European design, the presence of sawteeth yields larger towards-axis density penetration of higher atomic charges of impurities. It can be also seen that inclusion of sawtooth oscillation effects degrades the performance in the Chinese DEMO, but has positive impacts on the plasma performance in European and Indian DEMO due to the increase of the central ion density.