Effect of the magnetic field and current orientation on the splashing of liquid metal free surface of fusion reactor PFCs

Wang, Z.H.; Jia, Xin; Ni, Ming-Jiu

doi:10.1088/1741-4326/aade0c

Cited by 11 publications

(7 citation statements)

References 17 publications

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“…At this time, the thickness of the liquid film is about to exceed the sidewall of the flow channel, so the enlargement of the current intensity had no choice but to stop. Compared with the effect of current on the liquid metal under the condition of the insulating wall [14], the liquid metal on the conductive wall has higher stability, the height and diameter of the liquid column are more stable, and it is unlikely to produce splashed droplets. On the one hand, the conductivity of the conductive wall is equivalent to that of the fluid, so part of the current will flow through the conductive wall, as a result, the current flowing through the fluid is smaller.…”

Section: The Free Surface Flow Under Combined Action Of the Magnetic ...mentioning

confidence: 99%

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Experimental study on liquid metal free surface flow under magnetic and electric field for nuclear fusion

Meng¹,

Wang²,

Zhang³

2022

Nucl. Fusion

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In the future application of nuclear fusion, the liquid metal flows are considered to be an attractive option of the first wall of the Tokamak which can effectively remove impurities and improve the confinement of plasma. Moreover, the flowing liquid metal can solve the problem of the corrosion of the solid first wall due to high thermal load and particle discharge. In the magnetic confinement fusion reactor, the liquid metal flow experiences strong magnetic and electric, fields from plasma. In the present paper, an experiment has been conducted to explore the influence of electric and magnetic fields on liquid metal flow. The direction of electric current is perpendicular to that of the magnetic field direction, and thus the Lorentz force is upward or downward. A laser profilometer (LP) based on the laser triangulation technique is used to measure the thickness of the liquid film of Galinstan. The phenomenon of the liquid column from the free surface is observed by the high-speed camera under various flow rates, intensities of magnetic field and electric field. Under a constant external magnetic field, the liquid column appears at the position of the incident current once the external current exceeds a critical value, which is inversely proportional to the magnetic field. The thickness of the flowing liquid film increases with the intensities of magnetic field, electric field, and Reynolds number. The thickness of the liquid film at the incident current position reaches a maximum value when the force is upward. The distribution of liquid metal in the channel presents a parabolic shape with high central and low marginal. Additionally, the splashing, i.e., the detachment of liquid metal is not observed in the present experiment, which suggests a higher critical current for splashing to occur.

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Section: The Free Surface Flow Under Combined Action Of the Magnetic ...mentioning

confidence: 99%

“…The experimental results show that the critical current decreases with increasing magnetic field strength. Dimensionless Lorentz force of the critical current density for the splashing is calculated by the multiple linear regression [14].…”

Section: Introductionmentioning

confidence: 99%

Experimental study on liquid metal free surface flow under magnetic and electric field for nuclear fusion

Meng¹,

Wang²,

Zhang³

2022

Nucl. Fusion

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“…Their results indicate that magnetic damping vigorously hinders the flow of liquid metal. Wang et al 8 investigated the effect of current and magnetic field orientation on free surface instability and splashing of liquid metal PFC. In summary, magnetic damping remarkably changes the flow pattern of liquid metal, especially under a strong magnetic field environment.…”

Section: Introductionmentioning

confidence: 99%

Magnetic field control of three‐dimensional self‐driven multi‐physical thermoelectric system in metal energy storage

Chen

Wang

Chen

2022

Intl J of Energy Research

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Summary A thermoelectric generator system is an essential component in thermal energy storage. Through the interaction of magnetic field and thermoelectric current, the thermal energy of liquid metal can be converted into kinetic energy directly, which stirs up a flow without an external hydraulic pump. The effect of the magnetic field on the flow pattern, velocity, and heat transfer efficiency of the self‐driven thermoelectric system is investigated through three‐dimensional numerical simulation. The coupling effect of the magnetic field, temperature field, and velocity field are taken into consideration using the consistent conservative scheme and partitioned iteration algorithm for multi‐region. Hartmann number (Ha) and thermoelectric number (Te) are introduced to measure the relative strength of magnetic damping effect and Seebeck effect. When the magnetic field is small (Ha/Te1/4 ≤ 0.52), the Seebeck effect dominates the flow in the bulk flow region, the velocity of rotating flow increases with the magnetic field, the direction of the Lorentz force is consistent with the flow direction. The maximum velocity of the thermoelectric system occurs when Ha/Te1/4 ∼ 0.52. Hereafter, the flow is dominated by the magnetic damping effect, the velocity decays gradually. A rotating flow in a horizontal plane is resulted from the vertical magnetic field, while a rotating flow in a vertical plane results from a horizontal magnetic field. The latter flow structure gets a larger Nusselt number and lowers the decay rate of kinetic energy because it can transport heat downward more efficiently. The rate of working of the Lorentz force depends on the magnitudes of the Seebeck coefficient and temperature difference.

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“…They could be also resistant to neutron radiation owing to their liquid nature and the reduction of thermal stress in the solid parts of the component [5]. However, when working as a PFM, very high plasma currents through LMs in a strong magnetic field, as is present in fusion tokamaks, can produce magneto-hydrodynamic (MHD) effects and cause liquid splashing from the surface [6][7][8][9][10]. In particular, plasma disruptions and edge-localized modes (ELMs) increase the current density in the liquid and can cause Kelvin-Helmholtz (KH) [11] and Rayleigh-Taylor (RT) [12] instabilities [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Bubble formation in liquid Sn under different plasma loading conditions leading to droplet ejection

Brochard

Morgan

2021

Nucl. Fusion

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Liquid metals have been proposed as potential divertor materials for future fusion reactors, and surface stability is a vital requirement for such liquid metal divertors (LMDs). Capillary porous structures (CPSs) have been applied to the design of liquid metal targets as they can avoid MHD instability by surface tension and provide a stable liquid surface. However, our previous work has found that liquid Sn surfaces can be very unstable in hydrogen plasma even in cases without magnetic fields. To increase our understanding of the interaction of liquid Sn surfaces with plasmas, in this work we systematically investigated the surface behaviors of liquid Sn in different plasma exposures in linear plasma devices, either in Nano-PSI at low flux and without magnetic field, or in Magnum-PSI with strong magnetic field strength. Surface instability leading to droplet ejection has been observed and recorded in the experiments. The ejection of droplets is not dependent on magnetic fields and plasma currents, and is found to be dependent on the plasma species and plasma flux and surface temperature. The CPS meshes applied in the experiments cannot completely avoid droplet ejection but can decrease droplet size and lower droplet production rate. In H plasma, droplets were observed once Sn melted even at low fluxes. For the case of N plasma, the appearance of droplets started at a temperature marginally higher than tin-nitride decomposition temperature. Only at high fluxes (~ 10 23 -24 m -2 s -1 ) and high temperatures (900 -1000 °C) were a few droplets observed in Ar or He plasma. For all cases, the ejection velocities of most droplets were around 1 -5 m/s. Bubble formation, growth and bursting in the plasma-species-supersaturated liquid Sn is proposed as the primary mechanism for the ejection of droplets. Plasma-enhanced solubility is responsible for the achievement of H/N-supersaturated liquid Sn, while high plasma flux implantation is responsible for Ar/He-supersaturated liquid Sn. Once the concentration of plasma species in liquid Sn reaches a certain supersaturation level, nucleation and growth of bubbles occur due to the desorption of dissolved plasma species from the liquid Sn. The formation and bursting of bubbles have been directly observed in the experiment. The sizes of most bubbles were estimated in the range of 40 -400 µm or even smaller. A bubble growth model based on Sievert's and Henry's laws is invoked to describe bubble growth in liquid Sn.

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Effect of the magnetic field and current orientation on the splashing of liquid metal free surface of fusion reactor PFCs

Cited by 11 publications

References 17 publications

Experimental study on liquid metal free surface flow under magnetic and electric field for nuclear fusion

Experimental study on liquid metal free surface flow under magnetic and electric field for nuclear fusion

Magnetic field control of three‐dimensional self‐driven multi‐physical thermoelectric system in metal energy storage

Bubble formation in liquid Sn under different plasma loading conditions leading to droplet ejection

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