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Articoli di riviste sul tema "Thermionics"

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Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 19 febbraio 2022

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1

ZHANG, C. "EFFECT OF INELASTIC SCATTERING OF HOT ELECTRONS ON THERMIONIC COOLING IN A SINGLE-BARRIER STRUCTURE". International Journal of Modern Physics B 14, n. 14 (10 giugno 2000): 1451–57. http://dx.doi.org/10.1142/s0217979200001503.

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One of the important problems in thermionics using layered structures is the inelastic scattering of hot electrons in the electrodes and in the barrier region. Scattering in these systems is mainly via the electron–phonon interaction, or indirectly via the electron–electron interaction. In semiconductor heterostructures at room temperature, the LO-phonon plays a crucial role in thermalising electrons. In this work we study the effect of electron–phonon scattering on thermionic cooling in a single-barrier structure. Because of the asymmetry of the barrier under a bias, a larger fraction of the total energy loss will be dissipated in the hot electrode. As a result, we find that the theoretical thermal efficiency can increase due to limited electron–phonon scattering.

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2

Khoshaman, Amir H., Harrison D. E. Fan, Andrew T. Koch, George A. Sawatzky e Alireza Nojeh. "Thermionics, Thermoelectrics, and Nanotechnology: New Possibilities for Old Ideas". IEEE Nanotechnology Magazine 8, n. 2 (giugno 2014): 4–15. http://dx.doi.org/10.1109/mnano.2014.2313172.

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3

Humphrey, T. E., M. F. O’Dwyer, C. Zhang e R. A. Lewis. "Solid-state thermionics and thermoelectrics in the ballistic transport regime". Journal of Applied Physics 98, n. 2 (15 luglio 2005): 026108. http://dx.doi.org/10.1063/1.1977191.

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4

Marshall, Paul. "Making Old Television Technology Make Sense". VIEW Journal of European Television History and Culture 8, n. 15 (27 ottobre 2019): 32. http://dx.doi.org/10.18146/2213-0969.2019.jethc163.

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How does traditional analogue television work? That’s a question beyond the comfort zone of most media historians who may not be familiar with analogue electronics. Even young engineers know little of thermionics, cathode rays and a myriad of other forgotten technologies. This important facet of television’s history is now only recorded by older engineers and by amateur groups who collect these technologies. In this paper, I will show by using examples how material artefacts can help us understand television’s history more fully.

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5

Huang, Sunchao, Matthew Sanderson, Yan Zhang e Chao Zhang. "High efficiency and non-Richardson thermionics in three dimensional Dirac materials". Applied Physics Letters 111, n. 18 (30 ottobre 2017): 183902. http://dx.doi.org/10.1063/1.5006277.

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6

Khoshaman, Amir H., Andrew T. Koch, Mike Chang, Harrison D. E. Fan, Mehran Vahdani Moghaddam e Alireza Nojeh. "Nanostructured Thermionics for Conversion of Light to Electricity: Simultaneous Extraction of Device Parameters". IEEE Transactions on Nanotechnology 14, n. 4 (luglio 2015): 624–32. http://dx.doi.org/10.1109/tnano.2015.2426149.

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7

Voronovich, D. A. "Thermionic properties of lutetium borides single crystals". Functional materials 21, n. 3 (30 settembre 2014): 266–73. http://dx.doi.org/10.15407/fm21.03.266.

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8

Koeck, F. A. M., J. M. Garguillo, John R. Smith, Y. J. Tang, G. L. Bilbro e Robert J. Nemanich. "Vacuum Thermionic Energy Conversion Based on Nanocrystalline Diamond Films". Advances in Science and Technology 48 (ottobre 2006): 83–92. http://dx.doi.org/10.4028/www.scientific.net/ast.48.83.

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Vacuum thermionic energy conversion achieves direct conversion of heat into electrical energy. The process involves thermionic electron emission from a hot surface and collection of the electrons on a cold surface where the two surfaces are separated by a small vacuum gap. Results are presented which indicate that nanocrystalline diamond films could lead to highly efficient thermionic energy conversion at temperatures less that 700°C. A critical element of the process is obtaining a stable, low work function surface for thermionic emission. Results are presented which establish that N-doped diamond films with a negative electron affinity can exhibit a barrier to emission of less than 1.6 eV. Films can be deposited onto field enhancing structures to achieve an even lower effective work function. Alternatively, nanocrystalline diamond films prepared with S doping exhibit field enhanced thermionic emission and an effective work function of ~1.9 eV. The field enhanced structures can reduce the effect of space charge and allow a larger vacuum gap. The possibility of a low temperature nanocrystalline diamond based thermionic energy conversion system is presented.

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9

Zhu, Weiwei, Cong Ji e Fan Gu. "Effects of heat transfer on characteristics of thermionic energy converter". Canadian Journal of Physics 96, n. 12 (dicembre 2018): 1247–58. http://dx.doi.org/10.1139/cjp-2017-0435.

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Photon enhanced thermionic emission (PETE) is a new concept in solar energy conversion, combining thermal and photovoltaic carrier excitations with thermionic emission. A solar-power-driven thermionic energy converter operates by illuminating the solar light condensed by a large-scale Fresnel lens to convert heat energy into electrical energy. By enhancing the efficiency of converting solar radiation into the emitter internal energy, the output power and efficiency of the thermionic energy converter can be greatly improved. In this study, using numerical simulations, the effects of emitter temperature and output characteristics on a thermionic energy converter were investigated. The results showed that the higher rate of the heating power represented the higher temperature of an emitter, as well as output current density, and efficiency. In addition, by reducing the diameter of a collector and thermal conductivity of insulation materials, or increasing the diameter of emitter, the temperature of emitter, output current density, and efficiency could be notably improved. It is also worth mentioning that the main factor that affected the emitter temperature in the process of heat transfer was heat conduction between solids. In conclusion, adequate illumination, reasonable size of collector and emitter, as well as appropriate insulation measurements could efficiently improve the output characteristics of thermionic energy converter.

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10

Galstian, I. Ye, E. G. Len, E. A. Tsapko, H. Yu Mykhailova, V. Yu Koda, M. O. Rud, M. Ya Shevchenko, V. I. Patoka, M. M. Yakymchuk e G. O. Frolov. "Low-Temperature Thermionic Converters Based on Metal–Nanostructured Carbon Composites". METALLOFIZIKA I NOVEISHIE TEKHNOLOGII 42, n. 4 (30 giugno 2020): 451–70. http://dx.doi.org/10.15407/mfint.42.04.0451.

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11

Mahan, G. D. "Thermionic refrigeration". Journal of Applied Physics 76, n. 7 (ottobre 1994): 4362–66. http://dx.doi.org/10.1063/1.357324.

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12

Gawkowski, Kamil, e Jarosław Sikora. "Selected methods of converting solar energy into electricity - comparative analysis". E3S Web of Conferences 49 (2018): 00029. http://dx.doi.org/10.1051/e3sconf/20184900029.

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This article presents selected methods of converting solar energy into electricity: photovoltaic cells (PV), converters which use photon-enhanced thermionic emission (PETE), and near-field enhanced thermionic energy conversion systems (NETEC). PETE and NETEC systems are innovative solutions that use the thermionic emission phenomenon and can replace photovoltaic generation of electricity. We did a comparative analysis of such issues as: structure, principle of operation, working temperature and with particular emphasis - efficiency. A comparison of these parameters is shown in the graphs and summarized in the table. Based on the analysis, we have drawn conclusions about previous achievements and development perspectives in the field of converting methods.

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13

Zhang, Xin, Zhuolin Ye, Shanhe Su e Jincan Chen. "Thermionic-Thermoradiative Converters". IEEE Electron Device Letters 39, n. 9 (settembre 2018): 1429–32. http://dx.doi.org/10.1109/led.2018.2859797.

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14

Mahan, G. D., e L. M. Woods. "Multilayer Thermionic Refrigeration". Physical Review Letters 80, n. 18 (4 maggio 1998): 4016–19. http://dx.doi.org/10.1103/physrevlett.80.4016.

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15

Larsson, Magnus, Vadim B. Antonyuk, A. G. Mal shukov, Zhongshui Ma e K. A. Chao. "Thermionic current reversal". Journal of Physics A: Mathematical and General 35, n. 35 (20 agosto 2002): L531—L534. http://dx.doi.org/10.1088/0305-4470/35/35/102.

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16

Perng, D. C., D. A. Crewe e A. D. Feinerman. "Micromachined thermionic emitters". Journal of Micromechanics and Microengineering 2, n. 1 (1 marzo 1992): 25–30. http://dx.doi.org/10.1088/0960-1317/2/1/006.

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17

HETRICK, ROBERT E., e A. L. SCHAMP. "Thermionic Gas Sensor". Combustion Science and Technology 96, n. 1-3 (gennaio 1994): 23–31. http://dx.doi.org/10.1080/00102209408935344.

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18

Rosul, Md Golam, Doeon Lee, David H. Olson, Naiming Liu, Xiaoming Wang, Patrick E. Hopkins, Kyusang Lee e Mona Zebarjadi. "Thermionic transport across gold-graphene-WSe2 van der Waals heterostructures". Science Advances 5, n. 11 (novembre 2019): eaax7827. http://dx.doi.org/10.1126/sciadv.aax7827.

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Solid-state thermionic devices based on van der Waals structures were proposed for nanoscale thermal to electrical energy conversion and integrated electronic cooling applications. We study thermionic cooling across gold-graphene-WSe2-graphene-gold structures computationally and experimentally. Graphene and WSe2 layers were stacked, followed by deposition of gold contacts. The I-V curve of the structure suggests near-ohmic contact. A hybrid technique that combines thermoreflectance and cooling curve measurements is used to extract the device ZT. The measured Seebeck coefficient, thermal and electrical conductance, and ZT values at room temperatures are in agreement with the theoretical predictions using first-principles calculations combined with real-space Green’s function formalism. This work lays the foundation for development of efficient thermionic devices.

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19

Klyuev, Alexey V., Arkady V. Yakimov e Irene S. Zhukova. "1/f Noise in Ti–Au/n-Type GaAs Schottky Barrier Diodes". Fluctuation and Noise Letters 14, n. 03 (29 giugno 2015): 1550029. http://dx.doi.org/10.1142/s0219477515500297.

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We have studied the forward current–voltage (I–V) characteristics of Ti–Au /n-type GaAs Schottky barrier diodes. However, we found some anomalies in I–V characteristics. Hence, we have considered a model that incorporates thermionic emission, thermionic-field emission and leakage components. Leakage component is linear and visible at rather small currents. The anomalies observed in the diode parameters were effectively construed in terms of the contribution of these multiple charge transport mechanisms across the interface of the diodes. It is shown that thermionic-field emission and leakage are the sources of low-frequency (1/f) noise in such type of diodes. Various Schottky diode parameters were also extracted from the I–V characteristics and current dependence of spectrum of 1/f voltage noise.

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20

Özden, Şadan, Cem Tozlu e Osman Pakma. "Temperature Dependent Electrical Transport in Al/Poly(4-vinyl phenol)/p-GaAs Metal-Oxide-Semiconductor by Sol-Gel Spin Coating Method". International Journal of Photoenergy 2016 (2016): 1–5. http://dx.doi.org/10.1155/2016/6157905.

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Deposition of poly(4-vinyl phenol) insulator layer is carried out by applying the spin coating technique ontop-type GaAs substrate so as to create Al/poly(4-vinyl phenol)/p-GaAs metal-oxide-semiconductor (MOS) structure. Temperature was set to 80–320 K while the current-voltage (I-V) characteristics of the structure were examined in the study. Ideality factor (n) and barrier height (ϕb) values found in the experiment ranged from 3.13 and 0.616 eV (320 K) to 11.56 and 0.147 eV (80 K). Comparing the thermionic field emission theory and thermionic emission theory, the temperature dependent ideality factor behavior displayed that thermionic field emission theory is more valid than the latter. The calculated tunneling energy was 96 meV.

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21

Xie, Kan, Steven Allen Hartz e Virginia M. Ayres. "Thermionic Field Emission Transport at Nanowire Schottky Barrier Contacts". MRS Proceedings 1785 (2015): 19–25. http://dx.doi.org/10.1557/opl.2015.605.

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ABSTRACTThe high carrier concentrations typically reported for nanowire devices indicate that when Schottky barrier transport is present, it occurs in the thermionic field emission regime with a substantial but not exclusive tunneling component. Analysis by thermionic field emission is difficult due to its multivariate nature. In recent work, we developed a mathematical stability approach that greatly simplified the evaluation of the multivariate thermionic field emission parameters. This is a general method with potentially wide applicability, requiring only the effective mass m* and relative dielectric constant εr for a given semiconductor as inputs. In the present work, we investigate the influence of the materials properties effective mass m* and relative dielectric constant εr on stability for a range of real and simulated semiconductor nanowires. A further investigation of temperature sensitivity and regime trends is presented.

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22

Lowke, J. J., e J. C. Quartel. "Use of Transport Coefficients to Calculate Properties of Electrode Sheaths of Electric Arcs". Australian Journal of Physics 50, n. 3 (1997): 539. http://dx.doi.org/10.1071/p96089.

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Particle conservation equations for electrons and positive ions, together with Poisson"s equation to account for space-charge effects on the electric field, have been solved for the electrode sheath regions of electric arcs. For thermionic cathodes and the anode, we find that the ambipolar diffusion approximation is generally valid. At the surface of the anode we find that there is generally a small retarding electric field. For non-thermionic cathodes and no ionisation due to the electric field in the sheath, we calculate unrealistically high sheath voltages and even then, find that the electric fields at the cathode surface are insufficient for field emission. It is suggested that photoionisation in the region close to the cathode may be a principal source of electrons for non-thermionic cathodes.

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23

Promros, Nathaporn, Suguru Funasaki, Motoki Takahara, Ryūhei Iwasaki, Mahmoud Shaban e Tsuyoshi Yoshitake. "Diode Parameters of Mesa Structural n-Type Nanocrystalline FeSi₂/p-Type Si Heterojunctions Prepared by Lift-Off Photolithography". Advanced Materials Research 1103 (maggio 2015): 91–96. http://dx.doi.org/10.4028/www.scientific.net/amr.1103.91.

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Mesa structural n-type nanocrystalline-FeSi2/p-type Si heterojunctions were successfully fabricated by a lift-off technique combined with a photolithography process. Their current-voltage characteristics were measured at low temperatures range from 300 K down to 60 K. We estimated their diode parameters such as ideality factor, barrier height and series resistance based on the thermionic emission theory and Cheung’s method. From the estimation by the thermionic emission theory, the obtained results show an increase of ideality factor and a decrease of barrier height at low temperatures. The estimation by Cheung’s method shows that the values of ideality factor and barrier height are in agreement with those obtained from the thermionic emission theory. The obtained series resistances from dV/d (lnJ)-J and H(J)-J plots, which are approximately equal to each others, are increased at low temperatures.

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24

Zuber, J. W., e C. Zhang. "Anisotropic thermionic response of Weyl semimetals with application in thermionic cooling". Journal of Applied Physics 128, n. 12 (28 settembre 2020): 125101. http://dx.doi.org/10.1063/5.0025078.

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25

BORDAS, C., B. BAGUENARD, B. CLIMEN, F. LÉPINE, F. PAGLIARULO, M. A. LEBEAULT e J. WILLS. "TIME AND ENERGY-RESOLVED THERMIONIC EMISSION IN CARBON CLUSTERS". International Journal of Modern Physics B 19, n. 15n17 (10 luglio 2005): 2899–909. http://dx.doi.org/10.1142/s0217979205031882.

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We present experimental measurements of time-dependent photoelectron spectra observed in thermionic emission of small carbon cluster anions and C 60 fullerenes. The combination of photoelectron velocity-map imaging with time-gated detection allowed to resolve delayed electron emission at different stages of the emission process. This unique capability allows us to analyze pure thermionic energy spectra under well-defined conditions. Experimental spectra are analyzed within the framework of the detailed balance theory.

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26

Voronovych, Daniil, Anatoliy Taran, Oksana Podshyvalova, Natalya Shitsevalova, Volodymyr Filipov e Anatoliy Dukhnenko. "Thermionic Emission of Yttrium Dodecaboride Single Crystal". Solid State Phenomena 289 (aprile 2019): 47–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.289.47.

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Experimental data on thermionic current density and electron work function of YB12 (100) at T = 1218 – 1978 K in high vacuum (p < 10-4 Pa) are first introduced. Temperature dependences of the thermionic current density and effective electron work function are presented without extrapolation to the zero-field currents because of the anomalous Schottky effect. The temperature dependences of theYB12 electron work function can be described by linear functions at certain temperature intervals. Preferential boron evaporation and additional ion bombardment by the residual gases ions and evaporated boron ions results in appearance of new phases depleted of boron on the YB12 surface. As a result, an YB4 – YB6 double layer on the YB12 single crystal surface has formed. The appearance of the new boride phases, depleted of boron, on the emitting surface causes an increase of thermionic current density compared with individual YB12.

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27

Pan, J., A. Gaibrois, M. Marripelly, J. Leung, S. Suko, M. Lee e T. Knight. "Effects of Very High Workfunction Metals or Metal Alloys (NiCr) on High Switching Speed, HV Schottky Diodes for Mixed Signal or RF ASIC". MRS Advances 5, n. 37-38 (2020): 1937–46. http://dx.doi.org/10.1557/adv.2020.336.

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AbstractFor high switching speed HV Schottky diodes, with very high work function metal and extremely lightly doped epi, the built-in potential may be too high for thermionic emission to occur, when the applied external voltage is quite low (near VF = 0.07V). If the epi is lightly doped p type, the built-in potential (VBuilt-in: potential difference between the metal and silicon Fermi levels) is 1.0V (measured with CV). If the external bias is 0.1V, near the measured VF, it is not enough to overcome the built-in potential for thermionic emission as illustrated. It is likely that in addition to thermionic emission, tunnelling and diffusion currents also contribute to the total HV Schottky diode forward current. TCAD simulation of HV Schottky diodes with N+ guard bands suggests the potential barrier and electric fields at the Schottky junction are relatively high for thermionic emission to occur, when external bias V ≈ VF. In this paper we report HV Schottky diodes fabricated with various metals, metal alloys and epitaxial films. Metal work functions and epi doping profiles are extracted with high frequency Capacitance-Voltage (CV) technique. 150V of breakdown voltage and very low forward voltage (VF = 0.07V) are demonstrated. The measured data indicate very high work function metal or metal alloy is needed to achieve high switching speed and low forward voltage.

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28

Kumar, Niraj, Anjana Kumari, Manisha Samarth, Rajiv Kumar e Tarun Dey. "Analytical Studies of Metal Insulator Semiconductor Schottky Barrier Diodes". Material Science Research India 11, n. 2 (3 novembre 2014): 121–27. http://dx.doi.org/10.13005/msri/110205.

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The current –voltage data of the metal –insulator semiconductor Schottky diode are simulated using thermionic emission diffusion equation taking into account the inter facial layer parameters.The computed current – voltage data are fitted into ideal thermionic emission diffusion equation to see the apparent effect of interfacial parameters on current transport.In presence of interfacial layer the Schottky contact behave as an ideal diode of apparently high barrier height. The behavior of apparent height and ideality factor with the presence of inter facial layer is discussed.

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29

Read, Frank H., e Nicholas J. Bowring. "Simulation of thermionic cathodes". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 531, n. 3 (ottobre 2004): 407–15. http://dx.doi.org/10.1016/j.nima.2004.05.092.

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Waldhauser, W., C. Mitterer, J. Laimer e H. Störi. "Sputtered thermionic hexaboride coatings". Surface and Coatings Technology 98, n. 1-3 (gennaio 1998): 1315–23. http://dx.doi.org/10.1016/s0257-8972(97)00263-6.

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31

Xuan, X. C. "Combined thermionic-thermoelectric refrigerator". Journal of Applied Physics 92, n. 8 (15 ottobre 2002): 4746–50. http://dx.doi.org/10.1063/1.1509101.

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Shakouri, Ali, e John E. Bowers. "Heterostructure integrated thermionic coolers". Applied Physics Letters 71, n. 9 (settembre 1997): 1234–36. http://dx.doi.org/10.1063/1.119861.

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Datas, A. "Hybrid thermionic-photovoltaic converter". Applied Physics Letters 108, n. 14 (4 aprile 2016): 143503. http://dx.doi.org/10.1063/1.4945712.

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Rasor, N. S. "Thermionic energy conversion plasmas". IEEE Transactions on Plasma Science 19, n. 6 (1991): 1191–208. http://dx.doi.org/10.1109/27.125041.

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Lushkin, O. Ye. "On Efficient Thermionic Cathodes". Ukrainian Journal of Physics 60, n. 1 (gennaio 2015): 74–90. http://dx.doi.org/10.15407/ujpe60.01.0074.

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Walder, Gerhard, e Olof Echt. "THERMIONIC EMISSION FROM FULLERENES". International Journal of Modern Physics B 06, n. 23n24 (dicembre 1992): 3881–91. http://dx.doi.org/10.1142/s0217979292001961.

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Fullerenes in the gas phase, excited by a pulsed laser, exhibit thermionic emission. We analyze the time dependence of the ion yield of C n + in a mass spectrometer. By pulsing the extraction field of the ion lens, we are able to observe delayed ions formed as late as 50 µs after excitation by the 2nd, 3rd or 4th harmonic of a Q-switched YAG laser. The enhanced sensitivity of this new technique allows us to detect delayed ions not only from excited C 60 and C 70, but from all other even-sized clusters in the size range 36≤ n ≤70. Our results do not confirm the assertion that thermionic emission from C 60 and C 70 can be characterized by just 2 or 3 distinct rate constants.

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Vezirov, Kh N. "Thermionic emission galvanomagnetic effect". Technical Physics Letters 24, n. 1 (gennaio 1998): 69–70. http://dx.doi.org/10.1134/1.1261998.

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Walder, Gerhard, Keith W. Kennedy e Olof Echt. "Thermionic emission from fullerenes". Zeitschrift f�r Physik D Atoms, Molecules and Clusters 26, S1 (marzo 1993): 288–90. http://dx.doi.org/10.1007/bf01425693.

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Taran, A. "Thermionic emission of LaB6-ZrB2 quasi-binary eutectic alloy with different ZrB2 fibers orientation". Functional Materials 20, n. 4 (25 dicembre 2013): 485–88. http://dx.doi.org/10.15407/fm20.04.485.

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Zhang, Wenwen, Wenxi Tian, Suizheng Qiu, Guanghui Su e Dalin Zhang. "ICONE23-1792 DEVELOPMENT OF TRANSIENT THERMAL-HYDRAULIC ANALYSIS CODE FOR THE SPACE THERMIONIC REACTOR". Proceedings of the International Conference on Nuclear Engineering (ICONE) 2015.23 (2015): _ICONE23–1—_ICONE23–1. http://dx.doi.org/10.1299/jsmeicone.2015.23._icone23-1_381.

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41

Rathkey, Doug. "Evolution and Comparison of Electron Sources". Microscopy Today 1, n. 4 (giugno 1993): 16–17. http://dx.doi.org/10.1017/s1551929500067432.

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Over the years, we've seen major developments in electron source technologies in response to the demands for better performance. This article presents a brief overview of the cathode technologies in use today.Two types of electron sources are used in commercially available scanning electron microscopes (SEMs), transmission electron microscopes (TEMs), scanning Auger microprobes, and electron beam lithography systems: thermionic and field emission electron cathodes. Thermionic cathodes reiease electrons from the cathode material when they are heated while field emission cathodes rely on a high electric field to draw electrons from the cathode material.

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Shida, João, Fangjian Wu, Eric Spieglan e Mesut Çalışkan. "Tungsten Thermionic Emission as a Gauge for Low Pressures of Cesium Vapor". Instruments 4, n. 4 (5 novembre 2020): 34. http://dx.doi.org/10.3390/instruments4040034.

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Heated metal filaments under electric fields and low pressures of alkali metal gas eject electrons by thermionic emission as a function of the pressure of the gas and the temperature of the filament. To explore this process in a program to develop large-area alkali metal photocathodes, we have designed and built a gauge following the studies of Taylor and Langmuir. We present proof-of-principle measurements of the thermionic emission of a tungsten filament in cesium vapor. We describe a second-generation design that corrects flaws in the first gauge.

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Christian, George, Menno Kappers, Fabien Massabuau, Colin Humphreys, Rachel Oliver e Philip Dawson. "Effects of a Si-doped InGaN Underlayer on the Optical Properties of InGaN/GaN Quantum Well Structures with Different Numbers of Quantum Wells". Materials 11, n. 9 (15 settembre 2018): 1736. http://dx.doi.org/10.3390/ma11091736.

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In this paper we report on the optical properties of a series of InGaN polar quantum well structures where the number of wells was 1, 3, 5, 7, 10 and 15 and which were grown with the inclusion of an InGaN Si-doped underlayer. When the number of quantum wells is low then the room temperature internal quantum efficiency can be dominated by thermionic emission from the wells. This can occur because the radiative recombination rate in InGaN polar quantum wells can be low due to the built-in electric field across the quantum well which allows the thermionic emission process to compete effectively at room temperature limiting the internal quantum efficiency. In the structures that we discuss here, the radiative recombination rate is increased due to the effects of the Si-doped underlayer which reduces the electric field across the quantum wells. This results in the effect of thermionic emission being largely eliminated to such an extent that the internal quantum efficiency at room temperature is independent of the number of quantum wells.

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44

Misra, Shikha, M. Upadhyay Kahaly e S. K. Mishra. "Thermionic emission from monolayer graphene, sheath formation and its feasibility towards thermionic converters". Journal of Applied Physics 121, n. 6 (14 febbraio 2017): 065102. http://dx.doi.org/10.1063/1.4975788.

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45

Wang, Yuwei, Gongtao Wu, Li Xiang, Mengmeng Xiao, Zhiwei Li, Song Gao, Qing Chen e Xianlong Wei. "Single-walled carbon nanotube thermionic electron emitters with dense, efficient and reproducible electron emission". Nanoscale 9, n. 45 (2017): 17814–20. http://dx.doi.org/10.1039/c7nr05388f.

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46

Khrapko, V. Yu. "The Concept of the Combined Thermal Protection System for Leading Edges of Hypersonic Vehicles with Use of Thermionic Emission". KnE Engineering 3, n. 3 (21 febbraio 2018): 465. http://dx.doi.org/10.18502/keg.v3i3.1647.

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This work represents a conceptual stage of the project on development of technology of the combined thermal protection system for hypersonic vehicles heat-stressed surfaces with use of technology of the thermionic power cell and thermal protection system with an external emission of electrons. The relevance of this work is to develop thermal protection system technology for aircraft, enabling prolonged controlled flight at hypersonic speeds, while providing low aerodynamic resistance and relative weight, the consistency of the geometric shape of the hypersonic vehicles leading edge. The various using types of thermal protection system are compared and the necessity to develop a new type of it using the effect of thermionic emission of electrons is proved. The scheme and the possible material composition of thermionic power cell with a reversed geometry of the electrodes are given. The problem of the choice of material for emission surface of the system with external electron emission and its manufacturing technology are discussed. Using cesium intercalated graphite as one of the possible coating materials is reviewed. A sequence of forthcoming studies is formulated at the stage of transition to the design basis for the operation of thermal protection of this type.

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47

Xu, Jin Jin, Zhong Zhu Gu, Xiao Li Xi, Wei Min Dai e Juan Juan Liu. "Loss Mechanism of Rare-Earth Tungsten Cathode Applied to High-Temperature Electrostatic Precipitation". Advanced Materials Research 113-116 (giugno 2010): 908–12. http://dx.doi.org/10.4028/www.scientific.net/amr.113-116.908.

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Rare-earth tungsten thermionic emission material was used in the high-temperature electrostatic dust removal technology. A static test facility was self-designed to explore the emission characteristic. XRD, SEM and EDS were used to analyze the microstructure and element distribution. Working in high-temperature and oxidizing condition, tungsten in the thermionic emission materials is oxidized to tungsten trioxide, but the rare-earth tungstate in the grain boundary has no chemical changes. In high-temperature and oxidizing ambience, there is oxidation and volatilization on the surface of rare-earth tungsten, resulting in materials loss. The degree of loss depends on the composition of gas.

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48

Wang, Wei Jun, Bo Chen, Jian Ping Zheng, Hua Zhen Lei, Li Jun Qi e Jun Zhao. "Study on Sorption Behavior of Cesium by Graphite". Materials Science Forum 847 (marzo 2016): 50–55. http://dx.doi.org/10.4028/www.scientific.net/msf.847.50.

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It has long been recognized that a need for practical methods for maintaining optimum cesium pressure within a thermionic energy converter has been pursued for space applications. An attractive solution to the problem is the use of a sorption type reservoir where cesium absorbed into a lattice. Four graphite materials were initially investigated for the potential usage as cesium storage media. Primary research focusing on the characteristics of loading ability, structural integrity, and dimensional change of these materials was performed by synthesizing proper cesium-graphite lamellar compounds with a two zone vapor transport method. Graphite foams show promising prospect for thermionic application as integral cesium reservoir material.

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49

Datas, A., e R. Vaillon. "Thermionic-enhanced near-field thermophotovoltaics". Nano Energy 61 (luglio 2019): 10–17. http://dx.doi.org/10.1016/j.nanoen.2019.04.039.

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50

Maruyama, S., M. Y. Lee, R. E. Haufler, Y. Chai e R. E. Smalley. "Thermionic emission from giant fullerenes". Zeitschrift f�r Physik D Atoms, Molecules and Clusters 19, n. 1-4 (marzo 1991): 409–12. http://dx.doi.org/10.1007/bf01448340.

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