Opto-Microactuator With Low-Thermal-Conductivity Material by Laser Heating

2002 ◽  
Author(s):  
Masahiro Ota ◽  
Atsunobu Noguchi
Keyword(s):  
Thermal Conductivity ◽  
Laser Beam ◽  
Gas Dynamics ◽  
Gas Flow ◽  
Glass Plate ◽  
Pyrex Glass ◽  
Beam Power ◽  
Molecular Gas ◽  
Carbon Coated ◽  
Ion Laser

A laser opto-microactuator is proposed in this paper. The effects of the thermal-conductivity of actuator materials on rotational phenomena are discussed. The actuator with 4 flat blades made of aluminum or Pyrex glass plate was installed in a vacuum chamber. By molecular gas dynamics effects, the actuator is rotated with the irradiation of argon ion laser beam. The blade surfaces of the actuator were coated by carbon black powder for absorbing laser beam power and heating the surfaces. Just after irradiating one blade surface of the actuator by the laser, the macroscopic gas flow is induced around the actuator at non-zero Knudsen number. By the reaction of the induced flow the actuator can rotate. This is the molecular gas dynamics effects (1)(2). The rotational rate of the actuator with Pyrex glass blades is faster than that of the actuator with aluminum blades. Because Pyrex glass has about 200 times or more of lower thermal-conductivity than that of the aluminum, then Pyrex glass blades maintain a lager temperature difference between front and rear surfaces and a large molecular gas dynamics effects. Also irradiating to the glass surface, Pyrex glass rotor can rotate counter-clock-wise of irradiating to carbon-coated surface.

Rotation of Laser Opto-Microactuator With Low-Heat-Conductivity Material

2001 ◽  
Author(s):  
Masahiro Ota ◽  
Atsunobu Noguchi
Keyword(s):  
Laser Beam ◽  
Heat Conductivity ◽  
Beam Power ◽  
Molecular Gas ◽  
Carbon Black Powder ◽  
Single Side ◽  
Laser Beam Power ◽  
Ion Laser ◽  
Coated Surface ◽  
Argon Ion

Abstract A laser opto-microactuator with four flat blades made of aluminum or Pyrex glass plates is proposed in this paper. The effects of the heat conductivity of the actuator materials on rotation phenomena are discussed. Through molecular gas dynamics effects, the actuator is rotated upon irradiation by an argon-ion laser beam. The blade surfaces of the actuator were coated with carbon black powder to absorb laser beam power and heat the surfaces. Three kinds of blades, noncoated, single-side-coated and both-sides-coated blades, were manufactured. The rotation rate of the actuator with both surfaces of one blade coated with the powder is faster than that of the actuator with only one surface coated with the powder because the total amount of radiation from the both-sides-coated surface is greater than that of a single-side-coated surface.

Molecular gas dynamics analysis on condensation coefficient of vapour during gas–vapour bubble collapse

2018 ◽  
Vol 856 ◽  
pp. 1045-1063 ◽  
Author(s):  
Kazumichi Kobayashi ◽  
Takahiro Nagayama ◽  
Masao Watanabe ◽  
Hiroyuki Fujii ◽  
Misaki Kon
Keyword(s):  
Gas Dynamics ◽  
Gas Flow ◽  
Bubble Radius ◽  
Density Ratio ◽  
Bubble Collapse ◽  
Molecular Gas ◽  
Dynamics Analysis ◽  
Condensation Coefficient ◽  
Evaporation And Condensation ◽  
Gas Molecules

This study investigates the influence of the condensation coefficient of vapour on the collapse of a bubble composed of condensable gas (vapour) and non-condensable gas (NC gas). We simulated vapour and NC gas flow inside a bubble based on the molecular gas dynamics analysis in order to replicate the phase change (viz., evaporation and condensation) precisely, by changing the initial number density ratio of the NC gas and vapour, the initial bubble radius and the value of the condensation coefficient. The results show that the motion of the bubble is unaffected by the value of the condensation coefficient when that value is larger than approximately 0.4. We also discuss NC gas drift at the bubble wall during the final stage of the bubble collapse and its influence on the condensation coefficient. We conclude that vapour molecules can behave as NC gas molecules when the bubble collapses, owing to the large concentration of NC gas molecules at the gas–liquid interface. That is, the condensation coefficient reaches almost zero when the bubble collapses violently.

scholarly journals GENERATION OF NANOPARTICLES IN THE CONCENTRATED ENERGY (LASER BEAM) AND GAS FLOW

Aviation ◽  
2004 ◽  
Vol 8 (3) ◽  
pp. 27-30 ◽  
Author(s):  
Arūnas Severas Amulevičius ◽  
Česlovas Steponas Sipavičius ◽  
Antanas Daugvila ◽  
Rimantas Davidonis
Keyword(s):  
Chemical Composition ◽  
Laser Beam ◽  
Energy Flow ◽  
Gas Flow ◽  
Beam Power ◽  
Particle Sizes ◽  
Laser Beam Power ◽  
Energy Laser ◽  
Size Of Particles ◽  
Selection Of

The method of generation and selection of small nanoparticles in the airflow is considered in this paper. To melt the material (stainless steel), a concentrated energy flow – a pulsed solid‐state laser beam – was used. Using the Mossbauer spectroscopy method, the particle sizes and their chemical composition at various distances from the melting place were determined. The influence of parameters of the laser beam power and the airflow on the size of particles and their chemical composition was investigated.

scholarly journals Carbon-coated Fe3O4 core–shell super-paramagnetic nanoparticle-based ferrofluid for heat transfer applications

2021 ◽  
Author(s):  
Mohd Imran ◽  
Nasser Zouli ◽  
Tansir Ahamad ◽  
Saad M. Alshehri ◽  
Mohammed Rehaan Chandan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
External Magnetic Field ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Carbon Coated ◽  
Core Shell Nanoparticles ◽  
Fe3o4 Core

Ferrofluids prepared by dispersing superparamagnetic Fe3O4@C core–shell nanoparticles in water exhibited exceptional enhancement in thermal conductivity without an external magnetic field.

scholarly journals Ultrafast carbothermal reduction of silica to silicon using a CO2 laser beam

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Seok-Ho Maeng ◽  
Hakju Lee ◽  
Min Soo Park ◽  
Suhyun Park ◽  
Jaeki Jeong ◽  
...  
Keyword(s):  
Carbon Black ◽  
Laser Beam ◽  
Carbothermal Reduction ◽  
Gas Flow ◽  
Crystalline Silicon ◽  
Reduction Process ◽  
Reaction Chamber ◽  
Raman Shift ◽  
Influence Of Process Parameters ◽  
Laser Beam Intensity

AbstractWe report the extraction of silicon via a carbothermal reduction process using a CO2 laser beam as a heat source. The surface of a mixture of silica and carbon black powder became brown after laser beam irradiation for a few tens of seconds, and clear peaks of crystalline silicon were observed by Raman shift measurements, confirming the successful carbothermal reduction of silica. The influence of process parameters, including the laser beam intensity, radiation time, nitrogen gas flow in a reaction chamber, and the molar ratios of silica/carbon black of the mixture, on the carbothermal reduction process is explained in detail.

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