Analysis on EAST LHCD Operation Space by Using Simple Core-SOL-Divertor Model

A simple core-SOL-divertor model （CSD model） was developed to investigate qual- itatively the overall features of the operational space for the integrated core and edge plasma. In the CSD model, the core plasma model of ITER physics guidelines and the two-point SOL-divertor model are applied, This CSD model is validated by the two dimensional divertor transport code （B2-EIRINE） and by the JT-60U divertor recycling database, and this model is applicable to the low- and high-recycling state of the divertor plasma. The CSD model is applied to the study of the EAST operational space with lower hybrid current drive under various kinds of trade-off for the basic plasma parameters, and the relationship between the operational space and the plasma discharge duration is also discussed.

Predictions for EAST Divertor Performance

A detailed study of the divertor performance in EAST has been performed for both its double null （DN） and single null （SN） configurations. The results of application of the SOLPS （B2-Eirene） code package to the analysis of the EAST divertor are summarized. In this work, we concentrate on the effects of increased geometrical closure and of magnetic topology variation on the scrape-off layer （SOL） and divertor plasma behavior. The results of numerical predictions for the EAST divertor operational window are also described in this paper. A simple Core-SOL- Divertor （C-S-D） model was applied to investigate the possibility of extending plasma operational space of low hybrid current drive （LHCD） experiments for EAST.

Study of Particle Behavior for Steady-State Operation in JT-60U

This paper summarizes recent studies of particle balance in long pulse discharges, long-term erosion/deposition and hydrogen retention for carbon divertor tiles, and particle behavior in SOL and divertor plasmas related to the two foregoing topics in JT-60U. Global saturation of the particle inventory appeared in the later phase of an ELMy H-mode plasma after several long pulse discharges. As for carbon divertor tiles, erosion was dominant in the outer divertor, and deposition was dominant in the inner divertor. Hydrogen isotope concentration （H＋D）/C in the deposition layer was estimated to be -0.032. The SOL plasma flow towards the inner divertor was observed at the low-field-side midplane, and influence of the E, x B drift flow from the outer divertor to the inner divertor via the private region on the divertor particle flux was evaluated to be large in the attached divertor plasmas. The preferential deposition in the inner divertor can be a consequence of these flows. For direct observation of the hydrogen molecular behavior in the divertor plasmas, hydrogen molecular line emission was measured and the fall in the emission intensity with distance from the divertor plates was reproduced by calculation with a neutral transport code and a collisional radiative modeling code.

Study of Scrape-Off-Layer Width in Ohmic and Lower Hybrid Wave Heated Double-Null Divertor Plasma in EAST

Edge profiles in Ohmic and lower hybrid （LH） wave heated discharges in EAST are presented. A comparison of the measured profiles is made with those from the theoretical prediction for the scrape-off-layer （SOL） width. The edge plasma parameters are diagnosed by a triple probe divertor diagnostic system and fast reciprocating probes at the outer mid-plane. The experimental results show that the SOL width of double-null （DN） divertor plasmas in EAST appears to exhibit a negative dependence on the power crossing the separatrix, which is consistent with the collisional SOL scalings of JET and Alcator C-Mod. This will provide useful information for extrapolation to the ITER SOL width scaling for power deposition.