The role of electron heat flux in guide-field magnetic reconnection

AbstractThe role of self generated magnetic fields in the transport of a heat wave following a nanosecond laser irradiation of a solid target is investigated. Magnetic fields are expected to localize the electron carrying the heat flux but at the same time are affected in their evolution by the heat flux itself. We performed simultaneous measurements of heat wave propagation velocity within the target and magnetic fields developing on the target surface. These were compared to results obtained by numerical magneto-hydrodynamic modeling, including self-generated B fields. The comparison shows that longitudinal heat flow is overestimated in the simulations. Similarly, but most notably, the radial expansion of the magnetic fields is underestimated by the modeling. The two are likely linked, the more pronounced radial drift of B-fields induces a rotation of heat flux in the radial direction, and corresponding longitudinal heat flux inhibition. This suggests the need for improving present modeling of self-generated magnetic fields evolution in high power laser-matter interaction.

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Fundamental role of ion viscosity on fast magnetic reconnection in large-guide-field regimes

Physics of Plasmas ◽

10.1063/1.3449589 ◽

2010 ◽

Vol 17 (6) ◽

pp. 060701 ◽

Cited By ~ 10

Author(s):

Andrei N. Simakov ◽

L. Chacón ◽

A. Zocco

Keyword(s):

Magnetic Reconnection ◽

Guide Field

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Critical role of electron heat flux on Bohm criterion

Physics of Plasmas ◽

10.1063/1.4971808 ◽

2016 ◽

Vol 23 (12) ◽

pp. 120701 ◽

Cited By ~ 8

Author(s):

Xian-Zhu Tang ◽

Zehua Guo

Keyword(s):

Heat Flux ◽

Critical Role ◽

Bohm Criterion ◽

Electron Heat

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On the Role of Marangoni Effects on the Critical Heat Flux for Pool Boiling of Binary Mixtures

Journal of Heat Transfer ◽

10.1115/1.2824021 ◽

1996 ◽

Vol 118 (1) ◽

pp. 103-109 ◽

Cited By ~ 52

Author(s):

W. R. McGillis ◽

V. P. Carey

Keyword(s):

Surface Tension ◽

Heat Flux ◽

Binary Mixtures ◽

Critical Heat Flux ◽

Full Range ◽

Pool Boiling ◽

Marangoni Effect ◽

Restoring Force ◽

Marangoni Effects

The Marangoni effect on the critical heat flux (CHF) condition in pool boiling of binary mixtures has been identified and its effect has been quantitatively estimated with a modified model derived from hydrodynamics. The physical process of CHF in binary mixtures, and models used to describe it, are examined in the light of recent experimental evidence, accurate mixture properties, and phase equilibrium revealing a correlation to surface tension gradients and volatility. A correlation is developed from a heuristic model including the additional liquid restoring force caused by surface tension gradients. The CHF condition was determined experimentally for saturated methanol/water, 2-propanol/water, and ethylene glycol/water mixtures, over the full range of concentrations, and compared to the model. The evidence in this study demonstrates that in a mixture with large differences in surface tension, there is an additional hydrodynamic restoring force affecting the CHF condition.

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Role of macrolayer evaporation in pool boiling at high heat flux

International Journal of Heat and Mass Transfer ◽

10.1016/0017-9310(86)90014-1 ◽

1986 ◽

Vol 29 (12) ◽

pp. 1953-1961 ◽

Cited By ~ 33

Author(s):

A.M. Bhat ◽

J.S. Saini ◽

R. Prakash

Keyword(s):

Heat Flux ◽

Pool Boiling ◽

High Heat ◽

High Heat Flux

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Near-Wall Microlayer Evaporation Analysis and Experimental Study of Nucleate Pool Boiling on Inclined Surfaces

Journal of Heat Transfer ◽

10.1115/1.2824329 ◽

1998 ◽

Vol 120 (3) ◽

pp. 641-653 ◽

Cited By ~ 12

Author(s):

G. F. Naterer ◽

W. Hendradjit ◽

K. J. Ahn ◽

J. E. S. Venart

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Heating Surface ◽

Nucleate Boiling ◽

Inclined Surfaces ◽

Wide Range ◽

Model Predictions ◽

Microlayer Evaporation ◽

Near Wall

Boiling heat transfer from inclined surfaces is examined and an analytical model of bubble growth and nucleate boiling is presented. The model predicts the average heat flux during nucleate boiling by considering alternating near-wall liquid and vapor periods. It expresses the heat flux in terms of the bubble departure diameter, frequency and duration of contact with the heating surface. Experiments were conducted over a wide range of upward and downward-facing surface orientations and the results were compared to model predictions. More active microlayer agitation and mixing along the surface as well as more frequent bubble sweeps along the heating surface provide the key reasons for more effective heat transfer with downward facing surfaces as compared to upward facing cases. Additional aspects of the role of surface inclination on boiling dynamics are quantified and discussed.

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Regulation of the normalized rate of driven magnetic reconnection through shocked flux pileup

Journal of Plasma Physics ◽

10.1017/s0022377821000659 ◽

2021 ◽

Vol 87 (3) ◽

Author(s):

Joseph Olson ◽

Jan Egedal ◽

Michael Clark ◽

Douglass A. Endrizzi ◽

Samuel Greess ◽

...

Keyword(s):

Magnetic Reconnection ◽

System Size ◽

Force Balance ◽

Absolute Rate ◽

Reconnection Rate ◽

Supersonic Plasma ◽

Reconnection Layer ◽

Inflow Conditions ◽

Theoretical Results

Magnetic reconnection is explored on the Terrestrial Reconnection Experiment (TREX) for asymmetric inflow conditions and in a configuration where the absolute rate of reconnection is set by an external drive. Magnetic pileup enhances the upstream magnetic field of the high-density inflow, leading to an increased upstream Alfvén speed and helping to lower the normalized reconnection rate to values expected from theoretical consideration. In addition, a shock interface between the far upstream supersonic plasma inflow and the region of magnetic flux pileup is observed, important to the overall force balance of the system, thereby demonstrating the role of shock formation for configurations including a supersonically driven inflow. Despite the specialized geometry where a strong reconnection drive is applied from only one side of the reconnection layer, previous numerical and theoretical results remain robust and are shown to accurately predict the normalized rate of reconnection for the range of system sizes considered. This experimental rate of reconnection is dependent on system size, reaching values as high as 0.8 at the smallest normalized system size applied.

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Eddy Modulation of Air–Sea Interaction and Convection

Journal of Physical Oceanography ◽

10.1175/2007jpo3545.1 ◽

2008 ◽

Vol 38 (1) ◽

pp. 65-83 ◽

Cited By ~ 20

Author(s):

Ivana Cerovečki ◽

John Marshall

Keyword(s):

Heat Flux ◽

Heat Budget ◽

Formation Rate ◽

Mean Flow ◽

Mode Water ◽

Ocean Eddies ◽

Eddy Heat Flux ◽

Water Formation ◽

Transformed Eulerian Mean

Abstract Eddy modulation of the air–sea interaction and convection that occurs in the process of mode water formation is analyzed in simulations of a baroclinically unstable wind- and buoyancy-driven jet. The watermass transformation analysis of Walin is used to estimate the formation rate of mode water and to characterize the role of eddies in that process. It is found that diabatic eddy heat flux divergences in the mixed layer are comparable in magnitude, but of opposite sign, to the surface air–sea heat flux and largely cancel the direct effect of buoyancy loss to the atmosphere. The calculations suggest that mode water formation estimates based on climatological air–sea heat flux data and outcrops, which do not fully resolve ocean eddies, may neglect a large opposing term in the heat budget and are thus likely to significantly overestimate true formation rates. In Walin’s watermass transformation framework, this manifests itself as a sensitivity of formation rate estimates to the averaging period over which the outcrops and air–sea fluxes are subjected. The key processes are described in terms of a transformed Eulerian-mean formalism in which eddy-induced mean flow tends to cancel the Eulerian-mean flow, resulting in weaker residual mean flow, subduction, and mode water formation rates.

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