One-dimensional model of detached plasmas in the scrape-off layer of a divertor tokamak

Abstract

Numerical and analytical study of a detached divertor equilibrium is presented. The model uses one-dimensional equations for continuity, momentum and energy balance with radiation, ionization, charge-exchange, and recombination processes. A reasonably simple neutral model is also employed. Analytical calculation, using a simple five-region model for a case with negligible convective heat flux and constant sources/sinks, captures the essence of detailed numerical calculation for the same case. More general cases are handled numerically. The detachment is studied as a function of the ratio Q⊥/S⊥ [the ratio of power and particle volume source, coming from the core to the scrape-off layer (SOL) region]. For low values of Q⊥/S⊥ (detached state), at the midplane and at the target, the ion temperature (Ti) is almost equal to the electron temperature (Te). As this ratio increases (attached state), Ti is larger than Te at the midplane. However at the target, Te is found to be slightly larger than Ti. It is also observed that as Q⊥/S⊥ increases, the region of most intense radiation shifts progressively from closer to the X-point towards the target plate.

1D Modeling of LHD Divertor Plasma and Hydrogen Recycling

“…2.1. They include interaction with neutrals and impurity cooling [4][5][6][7]. The differences of our model from those of precedent works are the neutral equations discussed in Sec.…”

Development of the Detachment under the Influence of the Supersonic Flow in the Divertor Region

“…If M t is known, the whole profile M (x) can be determined from Eq. (12). As it is already mentioned in [4,8], the different roots of this equation describe the plasma flow in the sub-and supersonic phase, respectively.…”

Fluid-particle hybrid simulation on the transports of plasma, recycling neutrals, and carbon impurities in the Korea Superconducting Tokamak Advanced Research divertor region

“…4͑b͒. 18,29,30 The size of the recycling zone can be represented by the distance between the plasma density peak and the divertor plate, and it amounts to a few centimeters for the illustrated cases in Fig. 4.…”

“…Recently, there was a numerical study that presented an intensive investigation of the detachment physics using a onedimensional simulation code incorporated with a neutral transport model that was simply tailored to match the Monte Carlo results or experimental data. 18 In the present numerical work, we aim to present a fully coupled fluid-kinetic hybrid modeling for plasma, neutral, and impurity particle transports in a two-dimensional domain with the capability of demonstrating the formation progress of a recycling zone. The resultant simulation code enables us to account for the detachment phenomena more rigorously while most existing numerical codes still appear to have certain limitations in such applications.…”