Abstract Details
| status: | file name: | submitted: | by: |
|---|---|---|---|
| approved | sherwood2023_atul.pdf | 2023-05-07 11:03:29 | Atul Kumar |
Abstracts
Author: Atul Kumar
Requested Type: Consider for Invited
Submitted: 2023-03-24 12:14:18
Co-authors: J. F. Caneses-Marin, C. Lau, R. Goulding
Contact Info:
Oak Ridge National Laboratory
1 Bethel Valley Road
Oak Ridge, Tennessee 37831
United States of Ame
Abstract Text:
The steady state linear divertor simulator ‘Material Plasma Exposure eXperiment’ (MPEX) is currently under construction at Oak Ridge National Laboratory with the goal of enabling plasma-material interaction studies at future fusion reactor relevant plasma conditions. The targets in MPEX will be exposed to 10^6 seconds to achieve an ion fluence of 10^31/m^2. Ion cyclotron heating (ICH) and electron cyclotron heating (ECH) are two auxiliary heating schemes used in MPEX to independently heat ions and electrons respectively and provide fusion divertor conditions ranging from sheath-limited to fully detached divertor regimes at a material target. A new massively parallel, HPC based, quasi-neutral Particle-In-Cell code-PICOS++ is developed and applied to understand the plasma transport in MPEX during radio-frequency (RF) based ICH. PICOS++ can model plasma transport for any open magnetic field systems with (1) Coulomb collisions in Fokker-Planck framework, (2) Volumetric particle source including Neutral Beam Injection, and (3) quasi-linear RF based ICH. The code is benchmarked with the fluid code SOLPS and validated against existing data from the Proto-MPEX experiments. The experimental observation of “density-drop” at the target during ICH discharges in Proto-MPEX has been demonstrated and explained via physics-based arguments with PICOS++ modeling. In fact, the density drops at the target in Proto-MPEX/MPEX to conserve the flux and compensate for the increased parallel flow during ICH. Furthermore, the modeling suggests that the “density-drop” behavior at the target saturates for higher RF power because of the strong dominance of parallel transport over collisional transport. This further leads to a two-temperature ion distribution at the target in MPEX. Finally, a complete study on the sensitivity of various plasma parameters with respect to ICH power is performed to investigate their effect on plasma transport and particle and energy flux at the target.
Comments: