scholarly journals Mathematical modeling of probe measurements in a supersonic flow of a four-component collisionless plasma

2020 ◽  
Vol 2020 (4) ◽  
pp. 97-109
Author(s):  
D.N. Lazuchenkov ◽  
◽  
N.M. Lazuchenkov ◽  
Keyword(s):  
Electrode Surface ◽  
Collisionless Plasma ◽  
Reference Electrode ◽  
Area Ratio ◽  
Ion Composition ◽  
Surface Area Ratio ◽  
Probe Current ◽  
Surface Areas ◽  
Probe System ◽  
Probe Measurements

The aim of this work is the development of a procedure for extracting the plasma electron density and temperature and ion composition from the current-voltage characteristic (C –V characteristic) of an isolated probe system of cylindrical electrodes. The plasma is four-component and consists of electrons, ions of two species with significantly different masses, and neutrals. The measuring probe and the reference electrode of the probe system may be made up of several cylinders. The electrodes of the probe system are placed transversely to a supersonic flow of a low-temperature collisionless plasma with a specified mass velocity. Using the familiar theoretical and experimental relationships for the ion and electron currents to a cylinder, a mathematical model of current collection is constructed for an isolated probe system at an arbitrary ratio of the electrode surface areas. The model includes the calculation of the equilibrium potential of the reference electrode as a function of the probe bias voltage. A procedure is developed for the identification of local plasma parameters using a priori information on the plasma properties and the experimental conditions. The effect of the electron density and temperature and the ion composition on the probe current of the isolated probe system at different ratios of the current-collecting electrode surface areas is studied. The ranges of the probe bias potentials and the values of the electrode surface area ratio that maximize and minimize the effect of the sought-for parameters on the probe current are determined. The quantitative restrictions on the bias potentials and the surface area ratio obtained in this study are used in the probe measurement procedure and in the objective function for comparing the theoretical approximation of the probe current with the measured I– characteristics. A numerical simulation of probe measurements under the ionospheric conditions was conducted to verify the efficiency of the procedure for extracting the local parameters of a four-component plasma from the electron branch of the I –V characteristic of an isolated probe system. The results obtained may be used in ionospheric plasma diagnostics onboard nanosatellites.

scholarly journals Estimation of probe measurements reliability in a supersonic flow of a four-component collisionless plasma

2021 ◽  
Vol 2021 (3) ◽  
pp. 57-69
Author(s):  
D.N. Lazuchenkov ◽  
◽  
N.M. Lazuchenkov ◽  
Keyword(s):  
Ionic Composition ◽  
Collisionless Plasma ◽  
Plasma Electron ◽  
Plasma Potential ◽  
Plasma Parameters ◽  
Probe Current ◽  
Bias Potential ◽  
Probe System ◽  
Parametric Studies ◽  
Probe Measurements

The aim of this work is to estimate the reliability of extracting the plasma electron density and temperature and ionic composition from the current-voltage (I-V) characteristic of an isolated probe system with cylindrical electrodes. An earlier proposed mathematical model of current collection by the probe system at positive bias potentials and an arbitrary ratio of the electrode areas is analyzed. The model is supplemented with a formula that determines, with an accuracy of several percent, the value of the bias potential at which the probe is under the plasma potential and the I-V characteristic splits into a transition and an electronic region. The analytical dependence of the bias potential on the plasma parameters and the ratio of the electrode areas made it possible to formalize the procedures for determining and assessing the reliability of the extracted plasma parameters using the regions of their strongest effect on the collected probe current. Parametric studies of the effect of the plasma parameters on the probe current were carried out for conditions close to measurements in the ionosphere. The paper demonstrates the feasibility of partitioning the sought-for plasma parameters into the regions of their strongest and weakest effect on the probe current in the range of the bias potentials considered. The problem of plasma parameter identification is formulated on the basis of a comparison of the probe current and the measured I-V characteristic in the L2 theoretical approximation. To each parameter there corresponds an objective function of its own, which differs in the domain of definition and the ratio of the electrode areas used in I-V characteristic measurements. Based on this formulation of the inverse problem in L2, estimates of the reliability of identification of the parameters of a plasma with two ion species are obtained depending on the errors of the model and probe measurements. The results obtained may be used in ionospheric plasma diagnostics.

Electrode and cuvette for rapid continuous CO2 tension and pH measurement in blood

1985 ◽  
Vol 59 (5) ◽  
pp. 1660-1664
Author(s):  
S. A. Katz ◽  
A. C. Roth ◽  
E. O. Feigl
Keyword(s):  
Carbonic Anhydrase ◽  
Response Time ◽  
Electrode Surface ◽  
Porous Ceramic ◽  
Reference Electrode ◽  
Silicone Membrane ◽  
Dimethyl Silicone ◽  
Glass Ph Electrode ◽  
Co2 Electrode ◽  
Ph Electrode

An electrode and cuvette system has been developed for the continuous and rapid measurement of either blood CO2 tension or pH. The CO2 electrode consists of a 1.5-mm-diameter flat-tip glass pH electrode covered by a film of carbonic anhydrase solution, over which a 25-micron-thick dimethyl silicone membrane is attached. Porous ceramic filled with 20% polyacrylamide, equilibrated with a salt solution, serves as a salt bridge between a Ag-AgCl reference electrode and the pH electrode surface. The electrode is housed in a four-port cuvette assembly. Blood from a vessel of interest is delivered to the cuvette by means of an occlusive roller pump. The cuvette maintains the electrode and blood at a constant temperature and directs a continuous jet of blood against the electrode surface. The cuvette also allows for easy and frequent calibration of the electrode with either gas or liquid standards. The 90% response time of the CO2 electrode is 3.0 s for liquids and 1.3 s for gases. Removal of the dimethyl silicone membrane and carbonic anhydrase film yields a pH electrode that can continuously measure blood pH with a 90% response time of 1.6 s.

Clinical implication of renal allograft volume to recipient body surface area ratio in pediatric renal transplant

2018 ◽  
Vol 22 (8) ◽  
pp. e13295
Author(s):  
Michael E. Chua ◽  
Jin Kyu Kim ◽  
Michele Gnech ◽  
Jessica M. Ming ◽  
Bisma Amir ◽  
...  
Keyword(s):  
Renal Transplant ◽  
Surface Area ◽  
Body Surface Area ◽  
Body Surface ◽  
Clinical Implication ◽  
Renal Allograft ◽  
Area Ratio ◽  
Surface Area Ratio ◽  
Pediatric Renal Transplant
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