scholarly journals Mathematical models for thermionic emission current density of graphene emitter

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Olukunle C. Olawole ◽  
Dilip K. De ◽  
Sunday O. Oyedepo ◽  
Fabian I. Ezema
Keyword(s):  
Mathematical Models ◽  
Current Density ◽  
Coefficient Of Thermal Expansion ◽  
Thermionic Emission ◽  
Emission Current Density ◽  
Least Square ◽  
Emission Current ◽  
Two Dimensional Materials ◽  
Current Emission ◽  
Thermionic Energy

AbstractIn this study, five mathematical models were fitted in the absence of space charge with experimental data to find a more appropriate model and predict the emission current density of the graphene-based thermionic energy converter accurately. Modified Richardson Dushman model (MRDE) shows that TEC's electron emission depends on temperature, Fermi energy, work function, and coefficient of thermal expansion. Lowest Least square value of $$S=\sum {\left({J}_{th}-{J}_{exp}\right)}^{2}=0.0002 \,\text{A}^{2}/\text{m}^{4}$$ S = ∑ J th - J exp 2 = 0.0002 A 2 / m 4 makes MRDE most suitable in modelling the emission current density of the graphene-based TEC over the other four tested models. The developed MRDE can be adopted in predicting the current emission density of two-dimensional materials and also future graphene-based TEC response.

A New Thermionic Cathode Based on Carbon Nanotubes with a Thin Layer of Low Work Function Barium Strontium Oxide Surface Coating

2008 ◽  
Vol 1142 ◽  
Author(s):  
Feng Jin ◽  
Yan Liu ◽  
Scott A Little ◽  
Chris M Day
Keyword(s):  
Work Function ◽  
Current Density ◽  
Enhancement Factor ◽  
Thermionic Emission ◽  
Field Enhancement ◽  
Oxide Coating ◽  
Emission Current Density ◽  
Emission Current ◽  
Strontium Oxide ◽  
Barium Strontium

ABSTRACTWe have created a thermionic cathode structure that consists of a thin tungsten ribbon; carbon nanotubes (CNTs) on the ribbon surface; and a thin layer of low work function barium strontium oxide coating on the CNTs. This oxide coated CNT cathode was designed to combine the benefits from the high field enhancement factor from CNTs and the low work function from the emissive oxide coating. The field emission and thermionic emission properties of the cathode have been characterized. A field enhancement factor of 266 and a work function of 1.9 eV were obtained. At 1221 K, a thermionic emission current density of 1.22A/cm2 in an electric field of 1.1 V/μm was obtained, which is four orders of magnitude greater than the emission current density from the uncoated CNT cathode at the same temperature. The high emission current density at such a modest temperature is among the best ever reported for an oxide cathode.

High emission current density, vertically aligned carbon nanotube mesh, field emitter array

2010 ◽  
Vol 97 (11) ◽  
pp. 113107 ◽  
Author(s):  
Chi Li ◽  
Yan Zhang ◽  
Mark Mann ◽  
David Hasko ◽  
Wei Lei ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Current Density ◽  
Emission Current Density ◽  
Emission Current ◽  
Field Emitter ◽  
High Emission ◽  
Vertically Aligned ◽  
Emitter Array ◽  
Field Emitter Array

Absolute emission current density of O− from 12CaO⋅7Al2O3 crystal

2002 ◽  
Vol 80 (22) ◽  
pp. 4259-4261 ◽  
Author(s):  
Q. X. Li ◽  
K. Hayashi ◽  
M. Nishioka ◽  
H. Kashiwagi ◽  
M. Hirano ◽  
...  
Keyword(s):  
Current Density ◽  
Emission Current Density ◽  
Emission Current

A new multiscale approach to rapidly determine the local emission current density of nanoscale metallic field emitters

2021 ◽  
Vol 130 (14) ◽  
pp. 144302
Author(s):  
J. Ludwick ◽  
M. Cahay ◽  
N. Hernandez ◽  
H. Hall ◽  
J. O’Mara ◽  
...  
Keyword(s):  
Current Density ◽  
Emission Current Density ◽  
Emission Current ◽  
Multiscale Approach ◽  
Field Emitters ◽  
Local Emission

scholarly journals Micro Flowers of SrS/Bi2S3 Nanocomposite and Its Field Emission Properties

2019 ◽  
Vol 3 (4) ◽  
pp. 105
Author(s):  
Aarti R. Gunjal ◽  
Ujjwala P. Chothe ◽  
Yogesh A. Sethi ◽  
Rajendra P. Panmand ◽  
Jalinder D. Ambekar ◽  
...  
Keyword(s):  
Field Emission ◽  
Current Density ◽  
Emission Current Density ◽  
Emission Current ◽  
Threshold Field ◽  
Light Illumination ◽  
Emission Properties ◽  
Field Emission Properties ◽  
Morphological Studies ◽  
A Current

The three-dimensional hierarchical SrS/Bi2S3 heterostructures were synthesized by a template-free single-step hydrothermal method. The structural and morphological studies revealed the formation of a single crystalline orthorhombic heterostructure with rod-like morphologies possessing a high aspect ratio. The field emission properties of SrS/Bi2S3 nanorods were investigated. J–E and the Fowler–Nordheim (F–N) plot, as well as long-term field emission (FE) stability, were studied. SrS/Bi2S3 nanoflowers have enhanced the FE properties more than the virgin Bi2S3. The observed values of the re-producible turn-on field for SrS/Bi2S3 defined to draw an emission current density of ca. 1 µA/cm2 were found to be ca. 2.50 V/µm, and of the threshold field to draw a current density of ca. 10 µA/cm2 were found to be ca. 3.00 V/µm (without visible light illumination). A maximum emission current density of ca. 527 μA/cm2 was drawn without light and a current density of ca. 1078 μA/cm2 with light, which is higher than that of pristine Bi2S3.

Growth of Carbon Nanofibers on Electroless Ni-P Alloy Catalyst

2002 ◽  
Vol 740 ◽  
Author(s):  
T.K. Tsai ◽  
W.L. Liu ◽  
S.H. Hsieh ◽  
W.J. Chen
Keyword(s):  
Field Emission ◽  
Current Density ◽  
Small Diameter ◽  
Emission Current Density ◽  
Emission Current ◽  
Threshold Field ◽  
Random Orientation ◽  
Emission Properties ◽  
Field Emission Properties ◽  
Electroless Ni

ABSTRATECarbon nanotubes (CNTs) were grown by electroless Ni-P plated on silicon substrate in a microwave heating chemical vapor deposition (CVD) system with methane gas at 700 °C. The CNTs grown on Ni–P catalyst showed random orientation and small diameter around 15–30 nm. Field emission test results indicated that the Ni–P catalyzed-CNTs exhibited excellent field emission properties. The turn-on field was about 0.56 V/μm with an emission current density 10 μA/cm2 and the threshold field was 4.4 V/μm with an emission current density 10 mA/cm2. These excellent field emission properties may be attributed to the random orientation and small diameter of CNTs.

Electron Field Emission from Nano-Diamond Films

2001 ◽  
Vol 704 ◽  
Author(s):  
S.G. Wang ◽  
Q. Zhang ◽  
S.F. Yoon ◽  
J. Ahn ◽  
Q. Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Electric Field ◽  
Field Emission ◽  
Current Density ◽  
Diamond Films ◽  
Emission Current Density ◽  
Hydrogen Gas ◽  
Emission Current ◽  
Electron Field Emission ◽  
Electron Field

AbstractIn this paper, the field emission properties of nano-diamond films were investigated by measuring the curves of emission current density (J) versus applied electric field (E). The nano-diamond films were prepared on n-type (100) silicon substrate by microwave plasma enhanced chemical vapor deposition (MPECVD) technique using a gas mixture of nitrogen-methane-hydrogen. Field emission results show that, with increasing hydrogen gas flow ratio of [H2]/[N2+CH4+H2] from 0 to 10 %, diamond grain size increases from 5 to 60 nm, threshold electric field for electron field emission increases from 1.2 to 5.75 V/μm, and emission current density decreases from 820 to 560 μA/cm2, demonstrating that small grain size nano-diamond films are promising as a cathode material for low-field electron emitters.

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