Low Recycling Divertor for JET Burning Plasma Regime ($P_{\mathrm{DT}}$  &gt; 25 MW, $Q_{\mathrm{DT}}$  &gt; 5), Insensitive to Plasma Physics

Zakharov, L.; Allain, Jean Paul; Bennett, Samuel X.; Abdelghany, Muhammad; Bulgadaryan, D. G.

doi:10.1109/tps.2019.2953591

Cited by 4 publications

(2 citation statements)

References 13 publications

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“…These designs broadly fall under two categories: fast-flowing and slow/static LM surfaces. Slow/static LM-PFCs, being self-healing, primarily target improving the plasma performance [18] and protecting the underlying substrate [19]. Heat is transferred from the liquid to the solid through thermal conduction and dissipated by an active cooling mechanism.…”

Section: Introductionmentioning

confidence: 99%

Magnetohydrodynamics in free surface liquid metal flow relevant to plasma-facing components

Sun

Al-Salami

Khodak³

et al. 2023

Nucl. Fusion

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While flowing liquid metal plasma-facing components (PFCs) represent a potentially transformative technology to enable long-pulse operation with high-power exhaust for fusion reactors, magnetohydrodynamic (MHD) drag in the conducting liquid metal will reduce the flow speed. Experiments have been completed in the linear open-channel LMX-U device [Hvasta et al., Nucl. Fusion. 58 (2018) 01602] for validation of MHD drag calculations with either insulating or conducting walls, with codes similar to those used to design flowing liquid metal PFCs for a Fusion Nuclear Science Facility [Kessel et al., Fusion Science Technol. 75 (2019) 886]. We observe that the average channel flow speed decreased with the use of conducting walls and the strength of the applied transverse magnetic field. The MHD drag from the retarding Lorentz force resulted in an increase of the liquid metal depth in the channel that ‘piled up’ near the inlet, but not the outlet. As reproduced by OpenFOAM and ANSYS CFX calculations, the magnitude and characteristics of the pileup in the flow direction increased with the applied traverse magnetic field by up to 120%, as compared to the case without an applied magnetic field, corresponding to an average velocity reduction of ~ 45%. Particle tracking measurements confirmed a predicted shear in the flow speed, with the surface velocity increasing by 300%, despite the 45% drop in the average bulk speed. The MHD effect makes the bulk flow laminarized but keeps surface waves aligned along the magnetic field lines due to the anisotropy of MHD drag. The 3D fringe field and high surface velocity generate ripples around the outlet region. It was also confirmed that the MHD drag strongly depends on the conductivity of the channel walls, magnetic field, and volumetric flow rate, in agreement with the simulations and a developed analytical model. These validated models are now available to begin to determine the conditions under which the ideal liquid metal channel design of a constant flow speed and fluid depth could be attained.

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Section: Introductionmentioning

confidence: 99%

Magnetohydrodynamics in free surface liquid metal flow relevant to plasma-facing components

Sun

Al-Salami

Khodak³

et al. 2023

Nucl. Fusion

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“…This new confinement regime has the potential to dramatically simplify * Author to whom any correspondence should be addressed. multiple physics and engineering challenges in fusion energy development [4,5].…”

Section: Introductionmentioning

confidence: 99%

Toroidal plasma acceleration due to NBI fast ion losses in LTX-β

Hughes¹,

Capecchi²,

Elliott³

et al. 2021

Plasma Phys. Control. Fusion

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The recent Lithium Tokamak Experiment-Beta (LTX-β) upgrade includes the addition of neutral beam injection (NBI) in the same direction as the plasma current (co-I P ) and a new toroidal Mirnov array for MHD characterization. In initial NBI experiments, a spontaneously rotating n = 1 MHD mode is seen to accelerate during NBI in the counter-beam direction, accompanied by a rise in electron density consistent with the beam-injected inventory but without a clear increase in plasma pressure. Together with analytic and numerical modeling of beam optics and fast ion confinement, these observations indicate the prompt loss of all or nearly all beam ions. However, the same modeling also suggests that planned upgrades to the Ohmic heating system should provide the fast ion confinement necessary for beam heating and core fueling. A simple analytic model relates the momentum confinement time τ ϕ to the observed evolution of mode rotation due to the combination of NBI momentum coupling, fast ion loss ⃗ J × ⃗ B, and anomalous viscous torques, yielding τ ϕ values consistent with past measurements of electron energy confinement time τ E,e .

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Plasma facing components with capillary porous system and liquid metal coolant flow

Khodak

Maingi

2022

Physics of Plasmas

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Liquid metal can create a renewable protective surface on plasma facing components (PFC), with an additional advantage of deuterium pumping and the prospect of tritium extraction if liquid lithium (LL) is used and maintained below 450 °C, the temperature above which LL vapor pressure begins to contaminate the plasma. LM can also be utilized as an efficient coolant, driven by the Lorentz force created with the help of the magnetic field in fusion devices. Capillary porous systems can serve as a conduit of LM and simultaneously provide stabilization of the LM flow, protecting against spills into the plasma. Recently, a combination of a fast-flowing LM cooling system with a porous plasma facing wall (CPSF) was investigated [A. Khodak and R. Maingi, Nucl. Mater. Energy 26, 100935 (2021)]. The system takes an advantage of a magnetohydrodynamics velocity profile as well as attractive LM properties to promote efficient heat transfer from the plasma to the LL at low pumping energy cost, relative to the incident heat flux on the PFC. In the case of a disruption leading to excessive heat flux from the plasma to the LM PFCs, LL evaporation can stabilize the PFC surface temperature, due to high evaporation heat and apparent vapor shielding. The proposed CPSF was optimized analytically for the conditions of a fusion nuclear science facility [Kessel et al., Fusion Sci. Technol. 75, 886 (2019)]: 10 T toroidal field and 10 MW/m2 peak incident heat flux. Computational fluid dynamics analysis confirmed that a CPSF system with 2.5 mm square channels can pump enough LL so that no additional coolant is needed.

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Low Recycling Divertor for JET Burning Plasma Regime ($P_{\mathrm{DT}}$ > 25 MW, $Q_{\mathrm{DT}}$ > 5), Insensitive to Plasma Physics

Cited by 4 publications

References 13 publications

Magnetohydrodynamics in free surface liquid metal flow relevant to plasma-facing components

Magnetohydrodynamics in free surface liquid metal flow relevant to plasma-facing components

Toroidal plasma acceleration due to NBI fast ion losses in LTX-β

Plasma facing components with capillary porous system and liquid metal coolant flow

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