Abstract Details
Abstracts
Author: Bodhi Biswas
Requested Type: Poster
Submitted: 2025-03-14 17:22:17
Co-authors: S.J.Frank, Yu.V.Petrov, J.K.Anderson, J.F.Caneses, C.B.Forest, R.W.Harvey, D.A.Sutherland, M.Yu
Contact Info:
Realta Fusion
1200 JOHN Q HAMMONS DR
MADISON, WI 53717
US
Abstract Text:
The Wisconsin HTS Axisymmetric Mirror (WHAM) aims to operate in the classical confinement regime [1] and validate models used to scope reactor-relevant mirrors. But the presence of large edge neutral pressures can result in CX limited fast ion confinement. Integrated simulation of plasma and neutral transport is needed to model this CX dominated regime accurately, and to predict what neutral conditions are required to access classical mirror confinement.
Plasma transport in mirror geometry is modeled with the bounce-averaged Fokker-Planck code CQL3D-m [2]. It uses a fully non-linear collision operator, and self-consistently accounts for NBI fueling, axial losses, and the axial potential. Neutrals are modeled with KN1D [3], a 1D-2V Boltzmann solver. KN1D has been modified to include (a) wall recycling and (b) cylindrical geometry by extending to 1D-3V. The latter is needed to model interaction with sloshing ions. In WHAM, the hot ion gyroradius is comparable to the plasma radius. Accordingly, FLR corrections to the KN1D ion sources are included. These sources are coupled to CQL3D, and both codes are iterated through the Integrated Plasma Simulator [4].
Short duration NBI injection experiments in WHAM are conducted to validate this model. With edge neutral densities of order 1e18m-3, predicted stored energy decay rates match experimental shots. A scan of neutral density reveals three parameter regimes. At low neutral densities, classical confinement is achieved. At medium densities, CX results in a loss of hot sloshing ions, degrading ion confinement. At high densities, ionization of edge neutrals provides significant fueling, leading to high ion densities, albeit at low energies. Presently, WHAM lies in the medium to high neutrals regime with neutral edge densities of 1e17–1e18 m-3.
1) Endrizzi et al., JPP. 2023. 89.5. 2) Harvey and McCoy., Proc. IAEA. 1992. NTIS No. DE93002962. 3) LaBombard., MIT PSFC. 2001. Rep. RR-01-3. 4) Foley and Elwasif., ORNL. 2012.
Characterization: 5.0
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