Progress of Divertor Study on DEMO Design

Abstract

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.

Three-dimensional impurity transport modeling of neon-seeded and nitrogen-seeded LHD plasmas

“…Prediction of a plasma is essential for a reactor design to ensure safety margins to engineering limits and good controllability of discharges. Increase of core performance, enlargement of device size, and extension of discharge time leads to severe engineering issues such as high heat load on the plasma-facing components statically or dynamically [1,2] and accumulation of impurities and hydrogen isotopes on wall surfaces [3,4]. These issues are closely linked to divertor plasma transport.…”

Investigation of E-Divertor Plasma during Simultaneous Injection of Hydrogen and Impurity Gases into GAMMA 10/PDX by Using the LINDA Code

“…Numerical simulation studies have been effectively progressed to reveal the physical mechanism of divertor plasma physics [14][15][16][17][18]. A numerical simulation study is a powerful tool to explain the detailed physical mechanism related to the plasma detachment.…”

Japan’s Efforts to Develop the Concept of JA DEMO During the Past Decade

“…Numerical simulation is necessary to predict the behavior of divertor plasma and to find probable operation condition for divertor heat removal on DEMO. For the application to DEMO, a SONIC code [21][22][23][24] has been developed so as to treat multiple impurities seeding for plasma detachment in different divertor geometries. Previous interest in the early divertor simulation with the SONIC code was to find a solution for satisfying q div peak < 10 MW/m 2 .…”