Full time-dependent SOLPS-ITER simulation of the SPARC tokamak: actuator design for particle and divertor condition control

Jae Sun Park, Jeremy D. Lore, Matthew Reinke, Adam Q. Kuang, Sebastian De Pascuale, Alex Creely

Research output: Contribution to journalArticlepeer-review

Abstract

This paper presents the application of full time-dependent SOLPS-ITER simulations for actuator design in the SPARC tokamak. This study employs both the EIRENE module, a neutral solver, and the B2.5 plasma module in a time-dependent mode. This is in contrast to most SOLPS simulations, which focus on steady-state solutions, where the neutral distribution is evolved without any time limit or for a time step of 1 ⋅ 10 − 3 second, which is several orders of magnitude larger than the fluid plasma time step. The time-dependent EIRENE was tested with a fixed B2.5 background and compared with a simple conductance based model in a simplified pump chamber geometry. This comparison aimed to verify the reliability of the neutral relaxation timescale derived from the time-dependent EIRENE. Subsequently, a full time-dependent simulation was performed in a realistic geometry, with the Monte-Carlo neutral time step synchronized with the plasma fluid time step. The numerical setup of the code, including relative time steps and the size of the census data used to store Monte-Carlo particle information is considered. The full-time dependent simulations are then applied to inform the design of the SPARC louver structure, which affects divertor plasma parameters by regulating the neutral conductance from the divertor to the pump. The response of the plasma and neutral parameters was captured on a timescale that enables the design of the actuator to consider time-dependent control capability. It was found that changing the louver opacity has an equivalent effect as varying the gas throughput via puff actuation. Therefore, equivalent divertor plasma conditions can be obtained from both actuators, while the neutral pressure distribution in the pump and divertor differs for each actuator.

Original languageEnglish
Article number076036
JournalNuclear Fusion
Volume64
Issue number7
DOIs
StatePublished - Jul 2024

Keywords

  • SOLPS-ITER
  • SPARC
  • control
  • divertor SOL
  • gas puff
  • louver
  • time-dependent SOLPS

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