Grain surface temperature in noble gas discharges: Refined analytical model

2006 ◽  
Vol 13 (10) ◽  
pp. 104506 ◽  
Author(s):  
S. A. Khrapak ◽  
G. E. Morfill
Keyword(s):  
Surface Temperature ◽  
Analytical Model ◽  
Noble Gas ◽  
Gas Discharges ◽  
Grain Surface

Cleanup Rates of Trace Amounts of Radioactive Krypton in Various Noble Gas Discharges

1962 ◽  
Vol 33 (1) ◽  
pp. 230-231 ◽  
Author(s):  
C. Y. Bartholomew ◽  
G. Cassidy ◽  
A. R. LaPadula
Keyword(s):  
Noble Gas ◽  
Gas Discharges

scholarly journals Nautilus multi-grain model: Importance of cosmic-ray-induced desorption in determining the chemical abundances in the ISM

2018 ◽  
Vol 615 ◽  
pp. A20 ◽  
Author(s):  
Wasim Iqbal ◽  
Valentine Wakelam
Keyword(s):  
Grain Size ◽  
Surface Temperature ◽  
Gas Phase ◽  
Numerical Models ◽  
Cosmic Ray ◽  
Grain Sizes ◽  
Small Grains ◽  
Grain Model ◽  
Grain Surface ◽  
The Impact

Context. Species abundances in the interstellar medium (ISM) strongly depend on the chemistry occurring at the surfaces of the dust grains. To describe the complexity of the chemistry, various numerical models have been constructed. In most of these models, the grains are described by a single size of 0.1 μm. Aims. We study the impact on the abundances of many species observed in the cold cores by considering several grain sizes in the Nautilus multi-grain model. Methods. We used grain sizes with radii in the range of 0.005 μm to 0.25 μm. We sampled this range in many bins. We used the previously published, MRN and WD grain size distributions to calculate the number density of grains in each bin. Other parameters such as the grain surface temperature or the cosmic-ray-induced desorption rates also vary with grain sizes. Results. We present the abundances of various molecules in the gas phase and also on the dust surface at different time intervals during the simulation. We present a comparative study of results obtained using the single grain and the multi-grain models. We also compare our results with the observed abundances in TMC-1 and L134N clouds. Conclusions. We show that the grain size, the grain size dependent surface temperature and the peak surface temperature induced by cosmic ray collisions, play key roles in determining the ice and the gas phase abundances of various molecules. We also show that the differences between the MRN and the WD models are crucial for better fitting the observed abundances in different regions in the ISM. We show that the small grains play a very important role in the enrichment of the gas phase with the species which are mainly formed on the grain surface, as non-thermal desorption induced by collisions of cosmic ray particles is very efficient on the small grains.

scholarly journals A COMBINED USE OF FDM AND DOE METHOD TO DERIVE A NEW TRANSIENT SIMPLIFIED SEMI-ANALYTICAL MODEL: A CASE STUDY OF ANHYDRITE RADIANT SLAB

2020 ◽  
Vol 330 ◽  
pp. 01002
Author(s):  
Abdelatif Merabtine ◽  
Abdelhamid Kheiri ◽  
Salim Mokraoui
Keyword(s):  
Surface Temperature ◽  
Analytical Model ◽  
Numerical Models ◽  
Thermal Response ◽  
Sensitivity Study ◽  
Conventional Heating ◽  
Heating Systems ◽  
Combined Use ◽  
Scale Test ◽  
Radiant Floor Heating

Radiant floor heating systems (FHS) are considered as reliable heating systems since they ensure maintaining inside air temperature and reduce its fluctuations more efficiently than conventional heating systems. The presented study investigates the dynamic thermal response of an experimental FHS equipped with an anhydrite radiant slab. A new simplified model based on an analytical correlation is proposed to evaluate the heating radiant slab surface temperature and examine its thermal behavior under dynamic conditions. In order the validate the developed analytical model, an experimental scenario, under transient conditions, was performed in a monitored full-scale test cell. 2D and 3D numerical models were also developed to evaluate the accuracy of the analytical model. The method of Design of Experiments (DoE) was used to both derive meta-models, to analytically estimate the surface temperature, and perform a sensitivity study.

Calculated Values of the Parameters of Noble Gas Discharges

1954 ◽  
Vol 94 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Walter J. Graham ◽  
Arthur J. Ruhlig
Keyword(s):  
Noble Gas ◽  
Gas Discharges

Analytical Model to Predict Annual Soil Surface Temperature Variation

1995 ◽  
Vol 117 (2) ◽  
pp. 91-99 ◽  
Author(s):  
M. Krarti ◽  
C. Lopez-Alonzo ◽  
D. E. Claridge ◽  
J. F. Kreider
Keyword(s):  
Surface Temperature ◽  
Analytical Model ◽  
Annual Variation ◽  
Soil Surface ◽  
Weather Data ◽  
Phase Lag ◽  
Model Predictions ◽  
Soil Thermal Properties ◽  
Soil Surface Temperature ◽  
Surface Temperature Variation

An analytical model is developed to predict the annual variation of soil surface temperature from readily available weather data and soil thermal properties. The time variation is approximated by a first harmonic function characterized by an average, an amplitude, and a phase lag. A parametric analysis is presented to determine the effect of various factors such as evaporation, soil absorptivity, and soil convective properties on soil surface temperature. A comparison of the model predictions with experimental data is presented. The comparative analysis indicates that the simplified model predicts soil surface temperatures within ten percent of measured data for five locations.

Thermal Aspects of Grinding: The Effect of the Wheel Bond on Heat Transfer to an Abrasive Grain

1991 ◽  
Vol 113 (4) ◽  
pp. 395-401 ◽  
Author(s):  
M. W. Harris ◽  
A. S. Lavine
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Heat Conduction ◽  
Beneficial Effect ◽  
Surface Temperature ◽  
Thermal Damage ◽  
High Thermal Conductivity ◽  
Abrasive Grain ◽  
Grain Surface

Heat generated during grinding can cause thermal damage to the workpiece and wheel. It is therefore important to understand the thermal aspects of grinding. This paper addresses heat conduction into the wheel, by considering a single abrasive grain in contact with the workpiece. In particular, the effect of the bond material on conduction into the grain is investigated. The results for the grain surface temperature are given in terms of parameters describing the geometry and thermal properties of the grain and bond. The beneficial effect of a high thermal conductivity for both the grain and the bond is clearly demonstrated.

Striations of the convective type and feedback in low-pressure mercury/noble-gas discharges

1985 ◽  
Vol 28 (10) ◽  
pp. 3034 ◽  
Author(s):  
F. C. van den Heuvel ◽  
Q. H. F. Vrehen
Keyword(s):  
Noble Gas ◽  
Low Pressure ◽  
Gas Discharges

scholarly journals Micro/Nano Amorphization/Oxidation Of Silicon Induced By High Repetition Femtosecond Laser Pulses

2021 ◽  
Author(s):  
Amirkianoosh Kiani
Keyword(s):  
Solar Cell ◽  
Femtosecond Laser ◽  
Surface Temperature ◽  
Pulse Duration ◽  
Analytical Model ◽  
Repetition Rate ◽  
Crystalline Silicon ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
Laser Parameters

The main aim of this thesis is to develop a new method for direct micro/nano amorphization/oxidation of silicon using femtosecond laser irradiation and its applications in maskless lithography and solar cell fabrication. Amorphization and oxidation occur when crystalline silicon is exposed to the irradiation of femtosecond laser pulses below the ablation threshold. Mechanisms of morphization and oxidation were discussed and the surface temperature model was developed to study the relation between laser parameters and observed amorphization and oxidation. A systematic theoretical and experimental study of the influence of the laser parameters on the quality of amorphorized area and the size of the feature fabricated through amorphization has been studied. It was found that during the process of silicon amorphization and oxidation, the higher repetition rate of laser pulses yields smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model was developed for the calculation of the average surface temperature after n-pulses. The effect of the laser pulse width was investigated by developing an analytical model for the calculation of the non-dimensional surface temperature with various pulse widths. It was found from experimental and analytical results that for a constant power and repetition rate, an increase in the pulse duration corresponds to a significant increase in the surface temperature. It results in an increase in the amount of modified material as well as improvement of light absorption in the case of amorphization. The main aim of this thesis is to develop a new method for direct micro/nano amorphization/oxidation of silicon using femtosecond laser irradiation and its applications in maskless lithography and solar cell fabrication.Amorphization and oxidation occur when crystalline silicon is exposed to the irradiation of femtosecond laser pulses below the ablation threshold. Mechanisms of morphization and oxidation were discussed and the surface temperature model was developed to study the relation between laser parameters and observed amorphization and oxidation. A systematic theoretical and experimental study of the influence of the laser parameters on the quality of amorphorized area and the size of the feature fabricated through amorphization has been studied. It was found that during the process of silicon amorphization and oxidation, the higher repetition rate of laser pulses yields smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model was developed for the calculation of the average surface temperature after n-pulses.The effect of the laser pulse width was investigated by developing an analytical model for the calculation of the non-dimensional surface temperature with various pulse widths. It was found from experimental and analytical results that for a constant power and repetition rate, an increase in the pulse duration corresponds to a significant increase in the surface temperature. It results in an increase in the amount of modified material as well as improvement of light absorption in the case of amorphization.The amorphous silicon and silicon oxide can act as an etch stop. Therefore, maskless lithography iis possible with the direct patterning (amorphization and oxidation) of crystalline silicon. Experimental results have proved the feasibility of the proposed concepts. The thin-film of amorphous silicon generated on the silicon substrate has a potential for use in photovoltaic devices and solar cell fabrication. In comparison with previous methods, the direct oxidation/amorphization of silicon induced by the femtosecond laser is a maskless single-step technique which offers a higher flexibility and reduced processing time.

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