Thermal transport through fishbone silicon nanoribbons: unraveling the role of Sharvin resistance

Nanoscale ◽  
2019 ◽  
Vol 11 (17) ◽  
pp. 8196-8203 ◽  
Author(s):  
Lin Yang ◽  
Yang Zhao ◽  
Qian Zhang ◽  
Juekuan Yang ◽  
Deyu Li
Keyword(s):  
Free Path ◽  
Thermal Transport ◽  
Mean Free Path

The phonon mean free path increases with the fin width, boosting the Sharvin resistance at the constrictions.

Role of neutral-particle bombardment in dust–dust interactions in plasmas

2001 ◽  
Vol 65 (4) ◽  
pp. 257-272 ◽  
Author(s):  
Ya. K. KHODATAEV ◽  
G. E. MORFILL ◽  
V. N. TSYTOVICH
Keyword(s):  
Free Path ◽  
Particle Bombardment ◽  
Neutral Particle ◽  
Mean Free Path ◽  
Dust Particles ◽  
Neutral Particles ◽  
Additional Force ◽  
Numerical Coefficient ◽  
The Mean

It is shown that the interaction of dust with neutral plasma particles can lead to attractive forces between dust particles, both in the case where the distance between dust particles is less than the mean free path of neutral particles and in the case where it is greater. The expressions for attractive forces differs in the two limits only by a numerical coefficient. The additional force of dust interaction is found to be due to the neutrals created by recombination of charged plasma particles on the surface of dust particles. The influence of radiative dust cooling on dust–dust interaction is considered.

Heat Conduction in Nanostructured Materials Predicted by Phonon Bulk Mean Free Path Distribution

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Giuseppe Romano ◽  
Jeffrey C. Grossman
Keyword(s):  
Free Path ◽  
Nanostructured Materials ◽  
Thermal Transport ◽  
High Efficiency ◽  
Theoretical Models ◽  
Mean Free Path ◽  
Phonon Transport ◽  
Computational Effort ◽  
Boltzmann Transport ◽  
Computational Framework

We develop a computational framework, based on the Boltzmann transport equation (BTE), with the ability to compute thermal transport in nanostructured materials of any geometry using, as the only input, the bulk cumulative thermal conductivity. The main advantage of our method is twofold. First, while the scattering times and dispersion curves are unknown for most materials, the phonon mean free path (MFP) distribution can be directly obtained by experiments. As a consequence, a wider range of materials can be simulated than with the frequency-dependent (FD) approach. Second, when the MFP distribution is available from theoretical models, our approach allows one to include easily the material dispersion in the calculations without discretizing the phonon frequencies for all polarizations thereby reducing considerably computational effort. Furthermore, after deriving the ballistic and diffusive limits of our model, we develop a multiscale method that couples phonon transport across different scales, enabling efficient simulations of materials with wide phonon MFP distributions length. After validating our model against the FD approach, we apply the method to porous silicon membranes and find good agreement with experiments on mesoscale pores. By enabling the investigation of thermal transport in unexplored nanostructured materials, our method has the potential to advance high-efficiency thermoelectric devices.

scholarly journals A new regime of nanoscale thermal transport: Collective diffusion increases dissipation efficiency

2015 ◽  
Vol 112 (16) ◽  
pp. 4846-4851 ◽  
Author(s):  
Kathleen M. Hoogeboom-Pot ◽  
Jorge N. Hernandez-Charpak ◽  
Xiaokun Gu ◽  
Travis D. Frazer ◽  
Erik H. Anderson ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Free Path ◽  
Thermal Management ◽  
Thermal Transport ◽  
Heat Dissipation ◽  
Mean Free Path ◽  
Heat Sources ◽  
Nanoscale Systems ◽  
Nanoscale Thermal Transport ◽  
Thermal Therapies

Understanding thermal transport from nanoscale heat sources is important for a fundamental description of energy flow in materials, as well as for many technological applications including thermal management in nanoelectronics and optoelectronics, thermoelectric devices, nanoenhanced photovoltaics, and nanoparticle-mediated thermal therapies. Thermal transport at the nanoscale is fundamentally different from that at the macroscale and is determined by the distribution of carrier mean free paths and energy dispersion in a material, the length scales of the heat sources, and the distance over which heat is transported. Past work has shown that Fourier’s law for heat conduction dramatically overpredicts the rate of heat dissipation from heat sources with dimensions smaller than the mean free path of the dominant heat-carrying phonons. In this work, we uncover a new regime of nanoscale thermal transport that dominates when the separation between nanoscale heat sources is small compared with the dominant phonon mean free paths. Surprisingly, the interaction of phonons originating from neighboring heat sources enables more efficient diffusive-like heat dissipation, even from nanoscale heat sources much smaller than the dominant phonon mean free paths. This finding suggests that thermal management in nanoscale systems including integrated circuits might not be as challenging as previously projected. Finally, we demonstrate a unique capability to extract differential conductivity as a function of phonon mean free path in materials, allowing the first (to our knowledge) experimental validation of predictions from the recently developed first-principles calculations.

Magnetic multilayers of Fe/Au: role of the electron mean free path

1999 ◽  
Vol 11 (30) ◽  
pp. 5717-5722 ◽  
Author(s):  
M A Howson ◽  
B J Hickey ◽  
J Garfield ◽  
J Xu ◽  
P A Ryan ◽  
...  
Keyword(s):  
Free Path ◽  
Mean Free Path ◽  
Magnetic Multilayers ◽  
Electron Mean Free Path
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