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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Improved Multiscale Model of Heat Exchange at the Apex of Carbon Nanotube Fiber Cathodes
摘要： A multiscale model of field emission (FE) from carbon nanotube fibers (CNFs) is developed which includes a detailed treatment of the heat exchange mechanisms in the array of carbon nanotubes (CNTs) located at the tip of the fiber. The model takes into account Joule heating within the fiber, radiative cooling at the fiber apex, and the transition from Nottingham heating to Henderson cooling in the CNTs in the array at the apex of the fiber as the external electric field is increased. The model uses numerical calculations of the current emitted from each CNT and the energy exchange at their tips. The model predicts the fraction of CNTs being destroyed as a function of the applied external electric field. For the surviving CNTs, the model also predicts the fraction of CNTs either undergoing Henderson cooling or Nottingham heating for both the up and down sweeps of the applied external electrical field. This investigation sheds new light on the FE properties on CNFs.
关键词： carbon nanotube fibers,Multiscale Model,field emission,Henderson cooling,self-heating effects,Nottingham heating
更新于2025-09-23 15:21:21
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Plasmonic photothermal heating of gold nanostars in a real-size container: multiscale modelling and experimental study
摘要： The ability of noble metal nanoparticles (NPs) to convert light into heat has triggered a lot of scientific interest due to the numerous potential applications, including, e.g. photothermal therapy or laser-based nanopatterning. In order for such applications to be practically implemented, the heating behaviour of NPs embedded in their surrounding medium has to be thoroughly understood, and theoretical models capable of predicting this behaviour must be developed. Here we propose a multiscale approach for modelling the photothermal response of a large ensemble of nanoparticles contained within a cm-scale, real size container. Electromagnetic field, ray tracing and heat transfer simulations are combined in order to model the response of and analyzing the heating efficiency and temperature dynamics upon laser irradiation of nanostars and nanospheres suspensions contained within a common Eppendorf tube. To validate the model, gold nanostars are then synthesised and characterized by electron microscopy and optical spectroscopy. Laser-induced heating experiments are conducted by irradiating colloid-filled Eppendorf tubes with a 785 nm continuous wave laser and monitoring by a thermographic camera. The experimental results confirm that the proposed model has potential for predicting plasmonic nanoparticle suspensions in real-scale containers, at cm3 volumes.
关键词： multiscale model,gold nanoparticle,photothermal effect,gold nanostar,surface plasmon
更新于2025-09-11 14:15:04