The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
A Hilgers - One of the best experts on this subject based on the ideXlab platform.
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Interaction between biased sunlit electron collectors in an infinite‐Debye‐Length magnetoplasma: Electron temperature threshold effect
Journal of Geophysical Research, 1995Co-Authors: A HilgersAbstract:The interaction between two electrically coupled collectors in an infinite-Debye-Length magnetoplasma is studied by the use of a simple semianalytical model of particle collection by spherical probes. Because the ambient magnetic field confines the orbits of the particles, the perturbations due to photoelectron emission or screening of the ambient electron flux are “guided” along the magnetic field direction. When one collector is used as a density probe, depending on the size of the other collector with respect to the mean Larmor radius of the photoelectrons, the model predicts either an electron temperature threshold or a satellite potential threshold in order that the photoelectron current between the collectors overcomes the ambient electron current to the probe. This explains the variation of the modulation patterns of biased Langmuir probe measurements observed in the vicinity of auroral arcs.
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interaction between biased sunlit electron collectors in an infinite Debye Length magnetoplasma electron temperature threshold effect
Journal of Geophysical Research, 1995Co-Authors: A HilgersAbstract:The interaction between two electrically coupled collectors in an infinite-Debye-Length magnetoplasma is studied by the use of a simple semianalytical model of particle collection by spherical probes. Because the ambient magnetic field confines the orbits of the particles, the perturbations due to photoelectron emission or screening of the ambient electron flux are “guided” along the magnetic field direction. When one collector is used as a density probe, depending on the size of the other collector with respect to the mean Larmor radius of the photoelectrons, the model predicts either an electron temperature threshold or a satellite potential threshold in order that the photoelectron current between the collectors overcomes the ambient electron current to the probe. This explains the variation of the modulation patterns of biased Langmuir probe measurements observed in the vicinity of auroral arcs.
Hongyan Xu - One of the best experts on this subject based on the ideXlab platform.
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improving the triethylamine sensing performance based on Debye Length a case study on α fe2o3 nio cuo core shell nanorods sensor working at near room temperature
Sensors and Actuators B-chemical, 2017Co-Authors: Qi Xu, Zichao Zhang, Xiaopan Song, Shuai Yuan, Hongyan XuAbstract:Metal oxide semiconductor (MOS) based gas sensors for triethylamine (TEA) are anticipated with low operating temperature, high response, and robust manufacturing process. TEA sensors with the α-Fe2O3@NiO or α-Fe2O3@CuO core-shell nanorods (NRs) heterostructure are successfully fabricated and their sensing performance is optimized by controlling the shell thickness based on Debye Length. Porous α-Fe2O3 NRs are directly prepared on flat Al2O3 substrates by convenient hydrothermal process. The p-type shell layer is deposited by pulsed laser deposition (PLD) method, which width is controlled by changing the applied laser pulses. Due to the formation of PN heterojunction, the core-shell NR heterostructures show enhanced performances than pristine α-Fe2O3 NRs at near room-temperature, e.g. 40 °C. Moreover, such heterostructural sensor performances also exhibit a strong dependence on the shell thickness. When the p-type shell thickness is close to its Debye Length (λd), the core-shell sensor of the highest response is realized. The enhanced sensing properties of this core-shell NR heterostructure toward TEA can be explained by the increase of initial resistance (Ra) due to the modulation of depletion layer through optimizing the p-type shell thickness.
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Improving the triethylamine sensing performance based on Debye Length: A case study on α-Fe2O3@NiO(CuO) core-shell nanorods sensor working at near room-temperature
Sensors and Actuators B-chemical, 2017Co-Authors: Qi Xu, Zichao Zhang, Xiaopan Song, Shuai Yuan, Hongyan XuAbstract:Abstract Metal oxide semiconductor (MOS) based gas sensors for triethylamine (TEA) are anticipated with low operating temperature, high response, and robust manufacturing process. TEA sensors with the α-Fe 2 O 3 @NiO or α-Fe 2 O 3 @CuO core-shell nanorods (NRs) heterostructure are successfully fabricated and their sensing performance is optimized by controlling the shell thickness based on Debye Length. Porous α-Fe 2 O 3 NRs are directly prepared on flat Al 2 O 3 substrates by convenient hydrothermal process. The p-type shell layer is deposited by pulsed laser deposition (PLD) method, which width is controlled by changing the applied laser pulses. Due to the formation of PN heterojunction, the core-shell NR heterostructures show enhanced performances than pristine α-Fe 2 O 3 NRs at near room-temperature, e.g. 40 °C. Moreover, such heterostructural sensor performances also exhibit a strong dependence on the shell thickness. When the p-type shell thickness is close to its Debye Length ( λ d ), the core-shell sensor of the highest response is realized. The enhanced sensing properties of this core-shell NR heterostructure toward TEA can be explained by the increase of initial resistance ( R a ) due to the modulation of depletion layer through optimizing the p-type shell thickness.
Qi Xu - One of the best experts on this subject based on the ideXlab platform.
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improving the triethylamine sensing performance based on Debye Length a case study on α fe2o3 nio cuo core shell nanorods sensor working at near room temperature
Sensors and Actuators B-chemical, 2017Co-Authors: Qi Xu, Zichao Zhang, Xiaopan Song, Shuai Yuan, Hongyan XuAbstract:Metal oxide semiconductor (MOS) based gas sensors for triethylamine (TEA) are anticipated with low operating temperature, high response, and robust manufacturing process. TEA sensors with the α-Fe2O3@NiO or α-Fe2O3@CuO core-shell nanorods (NRs) heterostructure are successfully fabricated and their sensing performance is optimized by controlling the shell thickness based on Debye Length. Porous α-Fe2O3 NRs are directly prepared on flat Al2O3 substrates by convenient hydrothermal process. The p-type shell layer is deposited by pulsed laser deposition (PLD) method, which width is controlled by changing the applied laser pulses. Due to the formation of PN heterojunction, the core-shell NR heterostructures show enhanced performances than pristine α-Fe2O3 NRs at near room-temperature, e.g. 40 °C. Moreover, such heterostructural sensor performances also exhibit a strong dependence on the shell thickness. When the p-type shell thickness is close to its Debye Length (λd), the core-shell sensor of the highest response is realized. The enhanced sensing properties of this core-shell NR heterostructure toward TEA can be explained by the increase of initial resistance (Ra) due to the modulation of depletion layer through optimizing the p-type shell thickness.
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Improving the triethylamine sensing performance based on Debye Length: A case study on α-Fe2O3@NiO(CuO) core-shell nanorods sensor working at near room-temperature
Sensors and Actuators B-chemical, 2017Co-Authors: Qi Xu, Zichao Zhang, Xiaopan Song, Shuai Yuan, Hongyan XuAbstract:Abstract Metal oxide semiconductor (MOS) based gas sensors for triethylamine (TEA) are anticipated with low operating temperature, high response, and robust manufacturing process. TEA sensors with the α-Fe 2 O 3 @NiO or α-Fe 2 O 3 @CuO core-shell nanorods (NRs) heterostructure are successfully fabricated and their sensing performance is optimized by controlling the shell thickness based on Debye Length. Porous α-Fe 2 O 3 NRs are directly prepared on flat Al 2 O 3 substrates by convenient hydrothermal process. The p-type shell layer is deposited by pulsed laser deposition (PLD) method, which width is controlled by changing the applied laser pulses. Due to the formation of PN heterojunction, the core-shell NR heterostructures show enhanced performances than pristine α-Fe 2 O 3 NRs at near room-temperature, e.g. 40 °C. Moreover, such heterostructural sensor performances also exhibit a strong dependence on the shell thickness. When the p-type shell thickness is close to its Debye Length ( λ d ), the core-shell sensor of the highest response is realized. The enhanced sensing properties of this core-shell NR heterostructure toward TEA can be explained by the increase of initial resistance ( R a ) due to the modulation of depletion layer through optimizing the p-type shell thickness.
Leonardo Patacchini - One of the best experts on this subject based on the ideXlab platform.
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spherical conducting probes in finite Debye Length plasmas and e b fields
Plasma Physics and Controlled Fusion, 2011Co-Authors: Leonardo Patacchini, I H HutchinsonAbstract:The particle-in-cell code SCEPTIC3D (Patacchini and Hutchinson 2010 Plasma Phys. Control. Fusion 52 035005) is used to calculate the interaction of a transversely flowing magnetized plasma with a negatively charged spherical conductor, in the entire range of magnetization and Debye Length. The results allow the first fully self-consistent analysis of probe operation where neither the ion Larmor radius nor the Debye Length are approximated by zero or infinity. An important transition in plasma structure occurs when the Debye Length exceeds the average ion Larmor radius, as the sphere starts to shield the convective electric field driving the flow. A remarkable result is that in those conditions, the ion current can significantly exceed the unmagnetized orbital motion limit. When both the Debye Length and the Larmor radius are small compared with the probe dimensions, however, their ratio does not affect the collection pattern significantly, and Mach-probe calibration methods derived in the context of quasineutral strongly magnetized plasmas (Patacchini and Hutchinson 2009 Phys. Rev. E 80 036403) hold for Debye Lengths and ion Larmor radii smaller than about 10% of the probe radius.
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Spherical conducting probes in finite Debye Length plasmas and E × B fields
Plasma Physics and Controlled Fusion, 2011Co-Authors: Leonardo Patacchini, I H HutchinsonAbstract:The particle-in-cell code SCEPTIC3D (Patacchini and Hutchinson 2010 Plasma Phys. Control. Fusion 52 035005) is used to calculate the interaction of a transversely flowing magnetized plasma with a negatively charged spherical conductor, in the entire range of magnetization and Debye Length. The results allow the first fully self-consistent analysis of probe operation where neither the ion Larmor radius nor the Debye Length are approximated by zero or infinity. An important transition in plasma structure occurs when the Debye Length exceeds the average ion Larmor radius, as the sphere starts to shield the convective electric field driving the flow. A remarkable result is that in those conditions, the ion current can significantly exceed the unmagnetized orbital motion limit. When both the Debye Length and the Larmor radius are small compared with the probe dimensions, however, their ratio does not affect the collection pattern significantly, and Mach-probe calibration methods derived in the context of quasineutral strongly magnetized plasmas (Patacchini and Hutchinson 2009 Phys. Rev. E 80 036403) hold for Debye Lengths and ion Larmor radii smaller than about 10% of the probe radius.
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angular distribution of current to a sphere in a flowing weakly magnetized plasma with negligible Debye Length
Plasma Physics and Controlled Fusion, 2007Co-Authors: Leonardo Patacchini, I. H. HutchinsonAbstract:The influence of a weak magnetic field (B) on the ion current collected by a spherical electrode is studied by means of the 2v-3d particle in cell code SCEPTIC in the limit of zero Debye Length. The ion current dependence on B for low fields, shown to be linear, is compared with analytic expressions valid in the magnetized free-flight limit. In the flow-free regime, expressions for the angular distribution of current at different ion temperatures are provided. The configuration in which the plasma is drifting in the B-direction is investigated as well, and a Mach-probe calibration valid for equal temperature ions and electrons is given.
Gary W Slater - One of the best experts on this subject based on the ideXlab platform.
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simulations of free solution electrophoresis of polyelectrolytes with a finite Debye Length using the Debye huckel approximation
Physical Review Letters, 2012Co-Authors: Owen A Hickey, Tyler N Shendruk, James L Harden, Gary W SlaterAbstract:: We introduce a mesoscale simulation method based on multiparticle collision dynamics (MPCD) for the electrohydrodynamics of polyelectrolytes with finite Debye Lengths. By applying the Debye-Huckel approximation to assign an effective charge to MPCD particles near charged monomers, our simulations are able to reproduce the rapid rise in the electrophoretic mobility with respect to the degree of polymerization for the shortest polymer Lengths followed by a small decrease for longer polymers due to charge condensation. Moreover, these simulations demonstrate the importance of a finite Debye Length in accurately determining the mobility of uniformly charged polyelectrolytes and net neutral polyampholytes.
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effective Debye Length in closed nanoscopic systems a competition between two Length scales
Electrophoresis, 2006Co-Authors: Frederic Tessier, Gary W SlaterAbstract:The Poisson-Boltzmann equation (PBE) is widely employed in fields where the thermal motion of free ions is relevant, in particular in situations involving electrolytes in the vicinity of charged surfaces. The applications of this non-linear differential equation usually concern open systems (in osmotic equilibrium with an electrolyte reservoir, a semi-grand canonical ensemble), while solutions for closed systems (where the number of ions is fixed, a canonical ensemble) are either not appropriately distinguished from the former or are dismissed as a numerical calculation exercise. We consider herein the PBE for a confined, symmetric, univalent electrolyte and quantify how, in addition to the Debye Length, its solution also depends on a second Length scale, which embodies the contribution of ions by the surface (which may be significant in high surface-to-volume ratio micro- or nanofluidic capillaries). We thus establish that there are four distinct regimes for such systems, corresponding to the limits of the two parameters. We also show how the PBE in this case can be formulated in a familiar way by simply replacing the traditional Debye Length by an effective Debye Length, the value of which is obtained numerically from conservation conditions. But we also show that a simple expression for the value of the effective Debye Length, obtained within a crude approximation, remains accurate even as the system size is reduced to nanoscopic dimensions, and well beyond the validity range typically associated with the solution of the PBE.
