%0 Journal Article %1 liu:614 %A Liu, Yang %A Fisher, Timothy S. %D 2006 %E El-Genk, Mohamed S. %I AIP %J SPACE TECH.&APPLIC.INT.FORUM-STAIF 2006: 10th Conf Thermophys Applic Microgravity; 23rd Symp Space Nucl Pwr \ 4th Conf Human/Robotic Tech &Nat'l Vision for Space Explor.; 4th Symp Space Coloniz.; 3rd Symp on New Frontiers &Future Concepts %K nanostructured_materials quantum_wires thermionic_conversion thermionic_electron_emission %N 1 %P 614-622 %R 10.1063/1.2169242 %T Thermionic Energy Conversion with Nanoscale Materials and Devices %U http://link.aip.org/link/?APC/813/614/1 %V 813 %X Prior studies on electron emission show possibly beneficial effects of nanoscale phenomena on energy-conversion characteristics. For example, recent work has shown that the electric field around a nanoscale field emission device can increase the average energy of emitted electrons. This geometric effect could be useful in cooling devices based on the Nottingham effect. We consider here the hypothesis that nanoscale effects can favorably influence the energy-conversion efficiency and capacity of thermionic and field emission devices. Required improvements in experimental and computational tools for characterizing such effects include new methods of measuring electron energy distributions (EEDs) from nanoscale emitters and improved modeling of transport between bulk and quantum-confined materials. Accurate emission modeling requires calculation of a self-consistent solution to Schrödinger's equation and Poisson's equation. A particularly promising approach is the non-equilibrium Green's function (NEGF) formalism. Using NEGF, tractable solutions can be obtained for complex quantum problems because of several features inherent to the approach. For emission modeling, the primary benefit of the NEGF is that boundaries can be treated as bulk sources, which eliminates the need for periodic boundary conditions and enables the coupling of transport between bulk and confined materials. Recent work on EED measurements reveals indications of quantum confinement, as shown by the multiple peaks in the energy distribution. This paper includes representative simulation results and associated electron energy distribution measurements that identify interesting and potentially useful features of thermally excited electron emission phenomena. The paper concludes with recommendations for further study and engineering development.

@article{liu:614, abstract = {Prior studies on electron emission show possibly beneficial effects of nanoscale phenomena on energy-conversion characteristics. For example, recent work has shown that the electric field around a nanoscale field emission device can increase the average energy of emitted electrons. This geometric effect could be useful in cooling devices based on the Nottingham effect. We consider here the hypothesis that nanoscale effects can favorably influence the energy-conversion efficiency and capacity of thermionic and field emission devices. Required improvements in experimental and computational tools for characterizing such effects include new methods of measuring electron energy distributions (EEDs) from nanoscale emitters and improved modeling of transport between bulk and quantum-confined materials. Accurate emission modeling requires calculation of a self-consistent solution to Schrödinger's equation and Poisson's equation. A particularly promising approach is the non-equilibrium Green's function (NEGF) formalism. Using NEGF, tractable solutions can be obtained for complex quantum problems because of several features inherent to the approach. For emission modeling, the primary benefit of the NEGF is that boundaries can be treated as bulk sources, which eliminates the need for periodic boundary conditions and enables the coupling of transport between bulk and confined materials. Recent work on EED measurements reveals indications of quantum confinement, as shown by the multiple peaks in the energy distribution. This paper includes representative simulation results and associated electron energy distribution measurements that identify interesting and potentially useful features of thermally excited electron emission phenomena. The paper concludes with recommendations for further study and engineering development.}, added-at = {2007-08-07T20:24:17.000+0200}, author = {Liu, Yang and Fisher, Timothy S.}, biburl = {https://www.bibsonomy.org/bibtex/22513d96860f2f592c07c1466b51d1da1/essential.beatfinger}, description = {Thermionic Energy Conversion with Nanoscale Materials and Devices}, doi = {10.1063/1.2169242}, editor = {El-Genk, Mohamed S.}, interhash = {7b9c61c6ff664472f0b177fee78e125a}, intrahash = {2513d96860f2f592c07c1466b51d1da1}, journal = {SPACE TECH.\&APPLIC.INT.FORUM-STAIF 2006: 10th Conf Thermophys Applic Microgravity; 23rd Symp Space Nucl Pwr \ 4th Conf Human/Robotic Tech \&Nat'l Vision for Space Explor.; 4th Symp Space Coloniz.; 3rd Symp on New Frontiers \&Future Concepts}, keywords = {nanostructured_materials quantum_wires thermionic_conversion thermionic_electron_emission}, location = {Albuquerque, New Mexico (USA)}, number = 1, pages = {614-622}, publisher = {AIP}, timestamp = {2007-08-07T20:24:17.000+0200}, title = {Thermionic Energy Conversion with Nanoscale Materials and Devices}, url = {http://link.aip.org/link/?APC/813/614/1}, volume = 813, year = 2006 }