A Langmuir probe technique for measuring temperatures in a flame plasma

1977 ◽  
Vol 55 (1) ◽  
pp. 27-30 ◽  
Author(s):  
C. S. MacLatchy ◽  
J. R. Miner
Keyword(s):  
Langmuir Probe ◽  
Thermal Equilibrium ◽  
Temperature Gradients ◽  
Local Thermal Equilibrium ◽  
Simple Method ◽  
Probe Technique ◽  
Saha Equation ◽  
Flame Plasma ◽  
Relative Emissivity ◽  
Good Agreement

A simple method of measuring the temperature of a flame is presented. It is based on the use of a Langmuir probe and the assumption that the flame exhibits local thermal equilibrium so that the Saha equation can be applied. The method has been compared to measurements of temperature based on the relative emissivity of the Na D line at 5896 Å and shows good agreement except in regions where the flame is greatly perturbed or steep temperature gradients exist.

A Streamline Curvature Method for Calculating S1 Stream Surface Flow

1984 ◽  
Vol 106 (2) ◽  
pp. 306-312
Author(s):  
S. K. Mao ◽  
D. T. Li
Keyword(s):  
Surface Flow ◽  
Approximation Technique ◽  
Flow Section ◽  
Boolean Expression ◽  
Simple Method ◽  
Stream Surface ◽  
Streamline Curvature ◽  
Calculation Results ◽  
Good Agreement ◽  
Streamline Curvature Method

A streamline curvature method for calculating S1 surface flow in turbines is presented. The authors propose a simple method in which a domain of calculation can be changed into an orderly rectangle without making coordinate transformations. Calculation results obtained on subsonic and transonic turbine cascades have been compared with those of experiment and another theory. Good agreement has been found. When calculating blade-to-blade flow velocity at subsonic speed, a function approximation technique can be used in lieu of iteration method in order to reduce calculation time. If the calculated flow section is of a mixed (subsonic-supersonic) flow type, a Boolean expression obtained from the truth table of flow states is proposed to judge the integrated character of the mixed flow section. Similarly, another Boolean expression is used to determine whether there exists a “choking” of the relevant section. Periodical conditions are satisfied by iterating the first-order derivative of stagnation streamline, which is formed simultaneously. It can be proved that the stagnation streamline formed in this way is unique.

Direct comparison of turbulence measurements by Langmuir probe technique and by reflectometry

2006 ◽  
Vol 32 (8) ◽  
pp. 619-641 ◽  
Author(s):  
A. O. Urazbaev ◽  
V. A. Vershkov ◽  
S. V. Soldatov ◽  
D. A. Shelukhin
Keyword(s):  
Langmuir Probe ◽  
Turbulence Measurements ◽  
Probe Technique

scholarly journals Precise Measurements of CH Maser Emission and Its Abundance in Translucent Clouds

2021 ◽  
Vol 257 (2) ◽  
pp. 47
Author(s):  
Ningyu Tang ◽  
Di Li ◽  
Gan Luo ◽  
Carl Heiles ◽  
Sheng-Li Qin ◽  
...  
Keyword(s):  
Thermal Equilibrium ◽  
Column Density ◽  
High Sensitivity ◽  
Local Thermal Equilibrium ◽  
Molecular Gas ◽  
Excitation Temperature ◽  
Hyperfine Transitions ◽  
Visible Wavelengths ◽  
Log Normal ◽  
Log Normal Distribution

Abstract We present high-sensitivity CH 9 cm ON/OFF observations toward 18 extragalactic continuum sources that have been detected with OH 18 cm absorption in the Millennium survey with the Arecibo telescope. CH emission was detected toward 6 of the 18 sources. The excitation temperature of CH has been derived directly through analyzing all detected ON and OFF velocity components. The excitation temperature of CH 3335 MHz transition ranges from −54.5 to −0.4 K and roughly follows a log-normal distribution peaking within [−5, 0] K, which implies overestimation by 20% to more than 10 times during calculating CH column density by assuming the conventional value of −60 or −10 K. Furthermore, the column density of CH would be underestimated by a factor of 1.32 ± 0.03 when adopting local thermal equilibrium assumption instead of using the CH three hyperfine transitions. We found a correlation between the column density of CH and OH following log N(CH) = (1.80 ± 0.49) and log N(OH −11.59 ± 6.87. The linear correlation between the column density of CH and H2 is consistent with that derived from visible wavelengths studies, confirming that CH is one of the best tracers of H2 components in diffuse molecular gas.

scholarly journals A theoretical analysis of local thermal equilibrium in fibrous materials

2015 ◽  
Vol 19 (1) ◽  
pp. 69-82
Author(s):  
Mingwei Tian ◽  
Ning Pan ◽  
Lijun Qu ◽  
Xiaoqing Guo ◽  
Guangting Han
Keyword(s):  
Thermal Equilibrium ◽  
Internal Heat ◽  
Constant Heat Flux ◽  
Local Thermal Equilibrium ◽  
Transfer Model ◽  
Fibrous Materials ◽  
Two Phase ◽  
Convective Boundary ◽  
Boundary Problems ◽  
Criterion System

The internal heat exchange between each phase and the Local Thermal Equilibrium (LTE) scenarios in multi-phase fibrous materials are considered in this paper. Based on the two-phase heat transfer model, a criterion is proposed to evaluate the LTE condition, using derived characteristic parameters. Furthermore, the LTE situations in isothermal/adiabatic boundary cases with two different heat sources (constant heat flux and constant temperature) are assessed as special transient cases to test the proposed criterion system, and the influence of such different cases on their LTE status are elucidated. In addition, it is demonstrated that even the convective boundary problems can be generally estimated using this approach. Finally, effects on LTE of the material properties (thermal conductivity, volumetric heat capacity of each phase, sample porosity and pore hydraulic radius) are investigated, illustrated and discussed in our study.

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