Detached helium plasma simulation by a one-dimensional fluid code with detailed collisional-radiative model

Abstract

To increase the accuracy of a particle, momentum, and energy source terms in the detached helium plasma simulation, rate coefficients with the collisional-radiative model were introduced into the fluid code LINear Divertor Analysis (LINDA). Obtained effective rate coefficients and related source terms were compared with those from the conventional empirical databases. It is shown that a high-density condition in future fusion devices causes larger deviation between the effective and the empirical source terms. One-dimensional detached plasma simulation indicated that the peak amplitude of the plasma density during the rollover is sensitive to the source term difference related to the recombination. This study additionally revealed that the heating effect in the three-body recombination process strongly affects the detached plasma formation and downstream plasma parameters.

A point plasma model for linear plasma devices based on SOLPS-ITER equations: application to helium plasma

“…Thus, the investigation of such a species finds ample space among the current interests of the fusion community. Many experimental and computational studies were carried out in recent years: experimental detachment studies were performed in different LPDs, using helium as a working gas [29][30][31][32]; a detailed collisional-radiative model was implemented in a 1D fluid model for the study of a detached helium plasma in NAGDIS-II [33]; the effect of helium on plasmafacing materials (PFM), such as tungsten, were extensively studied in LPDs, showing a variety of different surface modifications [34][35][36][37]. Moreover, helium removes the complexities related to molecular species and it constitutes a suitable case-study for a newly developed model, allowing to reduce greatly the number of unknowns.…”

Effects from the Target Plate Geometry on Fluctuations of Helium Plasma in the Linear Divertor Simulator Magnum-PSI

“…In the edge plasma r < −10 mm, electron temperature and density are less than 0.3 eV and 1×10 20 m −3 , respectively. Compared to the plasma core, the recombination rate coefficient is elevated to over 5×10 −17 m 3 /s [21]. The threebody recombination is dominant in this lower T e range.…”

“…The rate coefficient for the recombination process, including the radiative recombination and three-body recombination, at n e ∼ 2.7 × 10 20 m −3 and T e ∼ 0.5 eV is approximately 3 × 10 −17 m 3 /s (from Ref. [21]), and the mean free path of the ions is approximately 0.7 m. In the lower electron temperature zone, the three-body recombination is predominant, T e < 2 eV. In the periphery, it was possible to witness the coherent emission fluctuations from neutral helium atoms created by the recombination of ions and electrons.…”

Transition from MAR to EIR of deuterium plasma detachment in NAGDIS-II

“…Hence, to quantitatively investigate the dependence of the plasma parameters on the neutral pressure, the electron static pressure, particle flux and heat flux were calculated based on the results from LTS. Firstly, the electron static pressures at the upstream and downstream positions were calculated using the equation P es = n e T e [31]. Figure 6 shows the radial distributions of the electron static pressures at the upstream and downstream locations as a function of P down .…”