Speaker
Description
Linear plasma devices employ analogous transport mechanisms to those in tokamaks, The plasma, constrained by magnetic fields, flows axially along field lines toward the target plate, enabling effective simulation of tokamak divertor conditions. The MPS-LD, owing to its simple structure and flexible parameter control, serves as an important experimental platform for investigating boundary plasma transport and divertor physics[1]. To achieve accurate divertor condition simulation, electron density and temperature near the MPS-LD target plate must be sufficiently increased. However, radial particle diffusion and energy losses impede parameter enhancement at the target. Therefore, a deeper understanding of boundary transport mechanisms is essential. Magnetic field configuration control is an effective approach to address this issue. Specific field configurations can significantly suppress radial losses, thus increasing particle and energy deposition on the target. Due to the spatial limitations of experimental diagnostics, numerical tools are essential for complementing experimental data and systematically simulating plasma transport processes. However, mainstream simulation codes (such as SOLPS-ITER [2]) face limitations in geometric adaptability and computational efficiency, making it difficult to achieve fast and flexible simulations for linear plasma devices. Therefore, it is imperative to develop dedicated simulation codes tailored to linear devices. To address this need, we developed LiFT (Linear Device Fluid Transport), a numerical code based on the 2D Braginskii equations, where both plasma and neutrals are modeled as fluids. LiFT employs a fourth-order finite-difference scheme for spatial discretization, significantly improving simulation accuracy while effectively suppressing numerical dissipation. Furthermore, an adaptive time-stepping algorithm is implemented to enhance computational efficiency. For hydrogen discharge experiments, the model validation was conducted sequentially, first for the plasma-only module and then for the coupled plasma-neutral fluid module. By comparing our simulations with BOUT++ [3] results and MPS-LD experimental data, the reliability of the code was confirmed. Based on this validation, LiFT was applied to systematically investigate the effects of diffusion and thermal conduction coefficients on radial transport and target plasma parameters. Further studies examined three magnetic field configurations (expanding, uniform, and magnetic mirror) and their impact on transport dynamics. Compared to a uniform field, the magnetic mirror configuration effectively reduces radial losses, resulting in higher electron temperature at the target.
Keywords: MPS-LD device; Boundary plasma transport; Braginskii equations
[1] Sun C et al 2021 Fusion Engineering and Design 162 112074.
[2] Alberti G et al 2023 Nucl. Fusion 63 026020.
[3] Dudson B D et al 2009 Computer Physics Communications 180 1467–80.