Effect of a weak ambipolar field on non-local heat transport using the non-diffusive approximation

We investigate the effect of a weak ambipolar field on non-local heat transport by solving the reduced Fokker-Planck equation in the non-diffusive approximation for the electron distribution function. It turns out that for a moderately high-Z plasma with steep gradients the maximum-heat-flow expression is modified and the ensuing results compare favourably with the experimental values. However, in the gentle-gradient limit the classical Spitzer-Härm heat flux expression is unaltered.

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Heat Flux in a Non-Maxwellian Solar Coronal Plasma

International Astronomical Union Colloquium ◽

10.1017/s0252921100154363 ◽

1989 ◽

Vol 104 (2) ◽

pp. 289-292

Author(s):

N.N. Ljepojevic ◽

P. MacNeice

Keyword(s):

Heat Flux ◽

Distribution Function ◽

High Velocity ◽

Coronal Loop ◽

Numerical Scheme ◽

Electron Distribution ◽

Electron Distribution Function ◽

Planck Equation ◽

Fourier Law ◽

Velocity Form

AbstractWe determine the electron distribution function within a hot coronal loop using a hybrid numerical scheme which couples the Spitzer-Härm method at low velocities with the solution to the high velocity form of the Landau-Fokker-Planck equation. From this we calculate the heat flux throughout the loop and compare it with the classical fourier law of Spitzer and Härm(1953).

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Heat transport and electron distribution function in laser produced plasmas with hot spots

Physics of Plasmas ◽

10.1063/1.1461385 ◽

2002 ◽

Vol 9 (5) ◽

pp. 2302-2310 ◽

Cited By ~ 33

Author(s):

O. V. Batishchev ◽

V. Yu. Bychenkov ◽

F. Detering ◽

W. Rozmus ◽

R. Sydora ◽

...

Keyword(s):

Distribution Function ◽

Heat Transport ◽

Hot Spots ◽

Electron Distribution ◽

Electron Distribution Function

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Effect of Fluid Loading on the Performance of Wicked Heat Pipes

Volume 3 ◽

10.1115/ht-fed2004-56403 ◽

2004 ◽

Author(s):

R. Kempers ◽

A. Robinson ◽

C. Ching ◽

D. Ewing

Keyword(s):

Heat Flux ◽

Heat Pipe ◽

Heat Transport ◽

Heat Pipes ◽

Working Fluid ◽

Fluid Loading ◽

Maximum Heat ◽

Horizontal Orientation ◽

Maximum Heat Flux ◽

Dry Out

A study was performed to experimentally characterize the effect of fluid loading on the heat transport performance of wicked heat pipes. In particular, experiments were performed to characterize the performance of heat pipes with insufficient fluid to saturate the wick and excess fluid for a variety of orientations. It was found that excess working fluid in the heat pipe increased the thermal resistance of the heat pipe, but increased maximum heat flux through the pipe in a horizontal orientation. The thermal performance of the heat pipe was reduced when the amount of working fluid was less than required to saturate the wick, but the maximum heat flux through the heat pipe was significantly reduced at all orientations. It was also found in this case the performance of this heat pipe deteriorated once dry-out occurred.

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Influence of Transverse Fins Attached to the Heated Wall of a Rayleigh-Be´nard Cavity

Heat Transfer, Volume 2 ◽

10.1115/imece2004-62124 ◽

2004 ◽

Cited By ~ 1

Author(s):

Darren L. Hitt ◽

Antonio Campo

Keyword(s):

Thermal Conductivity ◽

Nusselt Number ◽

Numerical Simulations ◽

Heat Transport ◽

Local Heat ◽

Heated Wall ◽

Lower Plate ◽

Maximum Heat ◽

Rayleigh Numbers ◽

Fin Spacing

In this article we examine the augmentation of classic Rayleigh-Be´nard convection by the addition of periodically-spaced tranverse fins attached to the heated, lower plate. The respective impacts of the fin size, the fin spacing and the thermal conductivity of the fin material are examined through numerical simulations for different laminar Rayleigh numbers and reported it terms of the Nusselt number. With the exception of very closely spaced fins, the heat transport is observed to exceed that of the idealized Rayleigh-Be´nard case. It is found that local heat transport maxima and minima do exist for specific fin spacings and that the maxima become more pronounced at higher Rayleigh numbers. For ‘small fins’ the fin spacing corresponding to maximum heat transport is such that the fin spacing is approximately equal to the enclosure height.

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Influence of the electron distribution function shape on nonlocal electron heat transport in laser-heated plasmas

Physical Review E ◽

10.1103/physreve.66.066414 ◽

2002 ◽

Vol 66 (6) ◽

Cited By ~ 14

Author(s):

F. Alouani Bibi ◽

J-P. Matte

Keyword(s):

Distribution Function ◽

Heat Transport ◽

Electron Distribution ◽

Electron Distribution Function ◽

Electron Heat ◽

Laser Heated ◽

Function Shape

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Absorption of ultra-short laser pulses and particle transport in dense targets

Laser and Particle Beams ◽

10.1017/s0263034606060332 ◽

2006 ◽

Vol 24 (2) ◽

pp. 231-234 ◽

Cited By ~ 8

Author(s):

M. SHERLOCK ◽

A. R. BELL ◽

W. ROZMUS

Keyword(s):

Distribution Function ◽

Electron Distribution ◽

Energy Transport ◽

Electron Distribution Function ◽

Planck Equation ◽

Front Surface ◽

Normal Incidence ◽

Laser Pulses ◽

Spatial Dimension ◽

Numerical Code

A new version of the numerical code KALOS has been developed to solve the Vlasov-Fokker-Planck equation for electrons as well as EM wave propagation. KALOS represents the electron distribution function in momentum space by an expansion in spherical harmonics. Its unique features make possible simultaneous investigations of fast electron generation and transport and the collisional evolution of thermal particles, including the return current of cold electrons. We report here on results obtained in one spatial dimension. Absorption of 100fs, 1015W/cm2laser pulses has been studied at normal incidence in sharp-edged dense plasmas. We have studied the effect on absorption of energy transport into the target as well as the deviation of the electron distribution function from Maxwellian. It is shown that it is necessary to take into account collisional heat transport into the target in order to correctly model the absorption rate at the front surface.

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Fokker-Planck simulations of ultrashort-pulse laser-plasma interactions

Laser and Particle Beams ◽

10.1017/s0263034600006704 ◽

1992 ◽

Vol 10 (3) ◽

pp. 461-471 ◽

Cited By ~ 6

Author(s):

L. Drska ◽

J. Limpouch ◽

R. Liska

Keyword(s):

Heat Flux ◽

Distribution Function ◽

Laser Radiation ◽

Electric Field ◽

Electron Distribution ◽

Electron Distribution Function ◽

Laser Pulses ◽

Ultrashort Laser Pulses ◽

Ultrashort Pulse Laser ◽

The Impact

The interaction of ultrashort laser pulses with a fully ionized plasma is investigated in the plane geometry by means of numerical simulation. The impact of the space oscillations in the amplitude of the laser electric field on the shape of the electron distribution function, on laser beam absorption, and on electron heat transport is demonstrated. Oscillations in the absorption rate of laser radiation with the minima coincident to the maxima of the laser electric field lead to a further decrease in the absorption of laser radiation. Heat flux in the direction of increasing temperature in the underdense region is caused by the modification of the electron distribution function and by the density gradient. A limitation of heat flux to the overdense plasma isobserved with the flux limiter in range 0.03–0.08, growing moderately with the intensity 1014–1016 W/cm2 of the incident 1.2-ps laser pulse.

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