Development of the Backflow Model for Simplified Impurity Exhaust in Monte‐Carlo Calculation

Contributions to Plasma Physics

Homma

Tokunaga

et al. 2018

Self Cite

The effects of multi‐impurity transport are important for the divertor plasma performance. To simulate the radiative divertor plasma precisely, we have extended the integrated divertor code, SONIC, to the simulation with multi‐impurity species. For SONIC extension, a new integrated modelling framework using the multiple‐program multiple‐data approach and message passing interface data exchange has been developed. In the framework, two impurities and more can be treated simultaneously with several Monte Carlo kinetic impurity codes. The extended SONIC code has been applied to analyse the JT‐60SA radiative divertor plasma. The SONIC simulation including multi‐impurity transport demonstrates that the radiative divertor plasma scenario compatible with the steady‐state high‐β plasma can be achieved.

Section: Multi‐impurity Sonic Simulation Of Jt‐60sa Radiative Divertomentioning

confidence: 99%

“…In previous SONIC simulations, such as, Refs. , one impurity species was treated using the MC kinetic model, and the other species were treated using a simple radiation model . In the simple radiation model, the impurity density is given as a fraction of the background ion density.…”

Section: Introductionmentioning

confidence: 99%

Multi‐impurity divertor simulation using a Monte Carlo kinetic impurity transport model

Contributions to Plasma Physics

Homma

Tokunaga

et al. 2018

Self Cite

“…The gas puff rate of the Ar impurity is adjusted to achieve f rad = 0.8. In order to reduce the calculation time for the impurity particle trace, the backflow model [17] is adopted. Figure 3 (a) shows the radial profiles of n e , the electron temperature T e and the ion temperature T i at the outer mid-plane.…”

Section: Divertor Plasma Analysis For the 8 Msized Demomentioning

confidence: 99%

Progress of Divertor Study on DEMO Design

Plasma and Fusion Research

Asakura

Tokunaga

et al. 2017

Recent progress of the physics and engineering design study for the 8 m-sized DEMO is reported. Parametric study for the divertor of the compact DEMO (a machine size ∼ 5.5 m) by using the SONIC code shows that the target heat load less than 10 MW/m 2 around the fusion power of ∼1.5 GW and the impurity radiation fraction of more than 80%. In the 8 m sized DEMO with these parameters, the partial detachment is obtained at the outer divertor, even in the low SOL density, due to the large impurity radiation in the SOL and divertor region. The SONIC simulation shows the peak of the target heat load is 7 MW/m 2 . However, the peak of the ion temperature at the target is considerably high, which causes significant erosion of the target. The divertor power handling and decrease in the ion temperature have to be proceeded by the scenario development of the divertor plasma operation as well as the core plasma design and the engineering design. In the engineering study side, the tungsten monoblock target with the water cooling and the Cu-alloy cooling tube is designed. The MCNP-5 neutronics analysis shows applicability of the Cu-alloy cooling tube for the divertor unit on the high heat flux region. Also the divertor cassette with a heat removability of peak heat load of 10 MW/m 2 is studied. The heat transport analysis shows the maximum temperature of 1021• C at the tungsten surface and 331• C at the Cu-alloy pipe, which are acceptable level for mechanical toughness and thermal fatigue.

“…In order to reduce the calculation time for long impurity exhaust process, the backflow model has been developed [16]. In the full calculation including the exhaust process, trajectories of injected impurity particles are traced until all particles are exhausted, i.e., weight of test particles becomes zero.…”

Section: (I) the Backflow Model For Simplified Impurity Exhaust Processmentioning

confidence: 99%

Divertor Study on DEMO Reactor

Plasma and Fusion Research

Asakura

Shimizu

et al. 2014

Huge power handling in the SOL/divertor region is one of the crucial issues for a tokamak fusion reactor. Divertor design study of a DEMO reactor with fusion power of 3 GW and ITER size plasma has progressed using the integrated divertor code SONIC. Recently, to improve conversion of the solution for the DEMO divertor plasma simulation, SONIC code has been improved. The calculation time is significantly reduced by (i) the backflow model for the simplified impurity exhaust process and (ii) optimization on HELIOS at BA-IFERC. In the SONIC simulation, the partial detached divertor plasma was obtained by the Ar impurity seeding. Although the plasma heat load at the outer target was reduced by the partial detachment, the contribution of the impurity radiation and the surface recombination of the fuel ions to the target heat load became large. As a result, the peak of the total target heat load was estimated to be 16 MW/m 2 . In order to reduce the total heat load, control of the impurity radiation profile by kind of seeding impurity species and the divertor geometry has been studied. They can decrease the target heat load, but the peak heat load is still larger than the heat removal capability of the present divertor target concept. Further design study including change of the machine specifications is necessary.