29th Symposium on Fusion Technology (SOFT 2016)

P1.115 Physics design study of the divertor power handling in 8m-sized DEMO reactor

5 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 115

Poster F. Plasma Facing Components P1 Poster session

Speaker

Kazuo Hoshino (Japan Atomic Energy Agency)

Description

Handling of the huge power exhausting from the core region to the SOL/divertor region is one of the crucial issues for a DEMO reactor design. In previous study for JA compact DEMO concept, SlimCS (a major radius of 5.5m), numerical simulation by an integrated divertor codes SONIC showed the divertor target heat load of < 10 MW/m²2 for the fusion power of < 1.5 GW and the large impurity radiation fraction on the exhausted power (frad > 0.8) by the Ar gas seeding. Recently, JA-Model 2014 DEMO concept (a major radius of 8.5m, a plasma current of 14MA, a fusion power of ~1.5GW) has been proposed. In the concept, the operational density becomes low compared with previous concept SlimCS, due to the low Greenwald density of ~6.6x10¹⁹19 m^-3-3. The divertor power handling scenario with the divertor plasma detachment may become difficult in such low operational density. In this paper, a divertor power handling scenario with the detachment for the 8m-sized DEMO is studied by using SONIC code. Even in the case of the low SOL density of ~1.5x10¹⁹19 m^-3-3 at the outer mid-plane, the partial detachment at the outer divertor target is obtained due to large machine size and large frad of 0.8. The SONIC simulation shows the target heat load of ~7 MW/m²2. However, the divertor plasma is still attached at the region far from separatrix and the peak ion temperature exceeds 300 eV, which causes the significant target erosion. Effects of increasing the SOL density by the fuel gas puff, location of the gas puffing, the divertor geometry effects, etc. on reduction of the ion temperature are also studied.