Metal-tip-array field emission cathodes for X-ray tubes

2017 ◽  
Author(s):  
Xinghui Li ◽  
Deng Luo ◽  
Guodong Bai ◽  
Hanyan Li ◽  
Yinfu Hu ◽  
...  
Keyword(s):  
Field Emission ◽  
X Ray ◽  
Metal Tip ◽  
Field Emission Cathodes

scholarly journals ZnO Nanowire-Based Field Emission Devices Through a Microelectronic Compatible Route

2020 ◽  
Vol 15 (1) ◽  
pp. 1-6
Author(s):  
Michel Oliveira da Silva Dantas ◽  
Denise Criado ◽  
Alejandro Zuniga ◽  
Wellington Silva ◽  
Elisabete Galeazzo ◽  
...  
Keyword(s):  
Field Emission ◽  
Electrical Characterization ◽  
Electrical Current ◽  
Active Area ◽  
X Ray ◽  
Nanoscale Structures ◽  
Wide Range ◽  
Innovative System ◽  
Field Emission Devices ◽  
Field Emission Cathodes

Nanostructured zinc oxide (ZnO) has attracted considerable interest for a wide range of applications, including its use as an active layer in gas sensor devices and as promising emitters for field emission devices. Although it is interesting for FE purposes, the synthesis of this material can be complex and non-compatible with microelectronic processes. To overcome this issue, this paper explores ZnO nanowires growth through thermal oxidation of zinc thin films. We applied this IC-compatible procedure to fabricate field emission cathodes. Analyses of Raman spectroscopy, X‑ray photoelectron spectrometry, X‑ray diffractometry and scanning electron microscopy confirmed that the processes applied were well succeeded in obtaining nanoscale structures of ZnO with dimensions up to 4 micrometers in length and 30‑100 nanometers in diameter. Electrical characterization showed an intense electron field emission on the active area of the device, with a low turn-on electric field (2.4 volts/micrometer). An innovative system based on image processing allowed electrical current mapping throughout the active area of the devices, providing information about the uniformity of the emitted current. These results demonstrate that the low-complex fabrication procedures adopted as well as the ZnO nanomaterial itself are suitable for FE devices development.

scholarly journals Sputter Deposition of Nanocones for Field Emission

1997 ◽  
Vol 471 ◽  
Author(s):  
Alan F. Jankowski ◽  
Jeffrey P. Hayes
Keyword(s):  
Field Emission ◽  
Physical Vapor Deposition ◽  
Sputter Deposition ◽  
Flat Panel Displays ◽  
X Ray ◽  
The Past ◽  
Physical Vapor Deposition Method ◽  
Sputter Deposited ◽  
Field Emission Cathodes ◽  
Emission Cathode

ABSTRACTDeposition into micron-sized holes is known to produce cone shapes as supported on substrates. Potential uses for the cones include field-forming devices as field ionizers and field emission cathodes. The application of such devices include flat panel displays and flash x-ray tubes. Process iterations to closely space arrays of sharp cones have been extensively documented during the past two decades using the physical vapor deposition method of evaporation. Sputter deposition is well known as a method to fill holes and trenches but has only recently been demonstrated as an alternative method to produce field emission cathodes. In a further reduction in size, we have been successful in demonstrating the ability to deposit a cone shape into a cavity with a 300nm diameter hole. Through comparison to the results of electron-beam evaporative deposition, a sputter deposited nanocone appears to be suitable for use as a field emission cathode.

scholarly journals Перспективы использования рентгеновских трубок с автоэмиссионным катодом и "прострельным" анодом в диапазоне мягкого рентгеновского излучения

2020 ◽  
Vol 90 (11) ◽  
pp. 1806
Author(s):  
М.М. Барышева ◽  
С.Ю. Зуев ◽  
А.Я. Лопатин ◽  
В.И. Лучин ◽  
А.Е. Пестов ◽  
...  
Keyword(s):  
Field Emission ◽  
Grazing Incidence ◽  
Small Distance ◽  
Bremsstrahlung Spectrum ◽  
Characteristic Radiation ◽  
X Ray ◽  
Electrode Distance ◽  
Cathode Assembly ◽  
Soft Spectrum ◽  
Field Emission Cathodes

The use of field emission cathodes in the design of x-ray tubes requires the placement of a cathode assembly with a small distance from the anode, complicating the output of radiation. Most acute this problem occurs when generating a relatively soft spectrum with wavelengths of 1-10 nm: in this case, the accelerating voltage does not exceed several kilovolts, and the inter-electrode distance composes several hundred micrometers. In this work, we experimentally demonstrated the applicability of beryllium-based submicron films as “shot-through” anodes for generating the Be K line ( = 11.4 nm) and the associated bremsstrahlung spectrum. In particular, the characteristic radiation of a tube with a field emission blade cathode and a Be film anode was recorded within the scheme of a grazing incidence grating spectrometer. The characteristics of beryllium films necessary for the development of X-ray tubes of this type with a higher output power are determined.

scholarly journals Field Emission Cathodes to Form an Electron Beam Prepared from Carbon Nanotube Suspensions

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 260 ◽  
Author(s):  
Karolina Urszula Laszczyk
Keyword(s):  
Carbon Nanotube ◽  
Field Emission ◽  
X Ray ◽  
Current State ◽  
Emission Enhancement ◽  
Low Weight ◽  
Coherent Beams ◽  
Electron Microscopes ◽  
Increasing Demand ◽  
Field Emission Cathodes

In the first decade of our century, carbon nanotubes (CNTs) became a wonderful emitting material for field-emission (FE) of electrons. The carbon nanotube field-emission (CNT-FE) cathodes showed the possibility of low threshold voltage, therefore low power operation, together with a long lifetime, high brightness, and coherent beams of electrons. Thanks to this, CNT-FE cathodes have come ahead of increasing demand for novel self-sustaining and miniaturized devices performing as X-ray tubes, X-ray spectrometers, and electron microscopes, which possess low weight and might work without the need of the specialized equipped room, e.g., in a harsh environment and inaccessible-so-far areas. In this review, the author discusses the current state of CNT-FE cathode research using CNT suspensions. Included in this review are the basics of cathode operation, an evaluation, and fabrication techniques. The cathodes are compared based on performance and correlated issues. The author includes the advancement in field-emission enhancement by postprocess treatments, incorporation of fillers, and the use of film coatings with lower work functions than that of CNTs. Each approach is discussed in the context of the CNT-FE cathode operating factors. Finally, we discuss the issues and perspectives of the CNT-FE cathode research and development.

scholarly journals Small-Sized Flat-Tip CNT Emitters for Miniaturized X-Ray Tubes

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Hyun Jin Kim ◽  
Jun Mok Ha ◽  
Sung Hwan Heo ◽  
Sung Oh Cho
Keyword(s):  
Silver Nanoparticles ◽  
Electric Field ◽  
Field Emission ◽  
Enhancement Factor ◽  
Flat Surface ◽  
Field Enhancement ◽  
X Ray ◽  
Field Emission Properties ◽  
Inner Diameter ◽  
Metal Tip

Small tip-type CNT emitters with the diameter of 0.8 mm were fabricated for miniaturized X-ray tubes. The CNT emitters were prepared by dropping CNTs and silver nanoparticles on a flat surface of a W metal tip followed by annealing at 800°C for 2 h under vacuum. The CNT emitters exhibit good field emission properties with the threshold electric field of 1.15 V/μm and the field enhancement factor of 12,050. CNTs were well attached to a flat W tip surface without coating on the side plane of the tip, and thus beam divergence could be minimized. Consequently, a miniaturized X-ray tube with the inner diameter of 5 mm was successfully demonstrated using the tip-type CNT emitter.

Comparison of high-angle take-off and low-angle take-off EDX detector geometry of the HF-2000 FE-TEM

1993 ◽  
Vol 51 ◽  
pp. 252-253
Author(s):  
Y. Sato ◽  
T. Hashimoto ◽  
M. Ichihashi ◽  
Y. Ueki ◽  
K. Hirose ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Field Emission ◽  
Solid Angle ◽  
Energy Dispersive ◽  
Objective Lens ◽  
X Rays ◽  
High Angle ◽  
X Ray ◽  
Detector Geometry

Analytical TEMs have two variations in x-ray detector geometry, high and low angle take off. The high take off angle is advantageous for accuracy of quantitative analysis, because the x rays are less absorbed when they go through the sample. The low take off angle geometry enables better sensitivity because of larger detector solid angle.Hitachi HF-2000 cold field emission TEM has two versions; high angle take off and low angle take off. The former allows an energy dispersive x-ray detector above the objective lens. The latter allows the detector beside the objective lens. The x-ray take off angle is 68° for the high take off angle with the specimen held at right angles to the beam, and 22° for the low angle take off. The solid angle is 0.037 sr for the high angle take off, and 0.12 sr for the low angle take off, using a 30 mm2 detector.

scholarly journals Thermoelectric Generator Using Polyaniline-Coated Sb2Se3/β-Cu2Se Flexible Thermoelectric Films

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1518
Author(s):  
Minsu Kim ◽  
Dabin Park ◽  
Jooheon Kim
Keyword(s):  
Electron Microscopy ◽  
Electrical Conductivity ◽  
Field Emission ◽  
Photoelectron Spectroscopy ◽  
Thermoelectric Generator ◽  
Hydrothermal Reaction ◽  
Water Evaporation ◽  
Pani Film ◽  
Portable Devices ◽  
X Ray

Herein, Sb2Se3 and β-Cu2Se nanowires are synthesized via hydrothermal reaction and water evaporation-induced self-assembly methods, respectively. The successful syntheses and morphologies of the Sb2Se3 and β-Cu2Se nanowires are confirmed via X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), and field emission transmission electron microscopy (FE-TEM). Sb2Se3 materials have low electrical conductivity which limits application to the thermoelectric generator. To improve the electrical conductivity of the Sb2Se3 and β-Cu2Se nanowires, polyaniline (PANI) is coated onto the surface and confirmed via Fourier-transform infrared spectroscopy (FT-IR), FE-TEM, and XPS analysis. After coating PANI, the electrical conductivities of Sb2Se3/β-Cu2Se/PANI composites were increased. The thermoelectric performance of the flexible Sb2Se3/β-Cu2Se/PANI films is then measured, and the 70%-Sb2Se3/30%-β-Cu2Se/PANI film is shown to provide the highest power factor of 181.61 μW/m·K2 at 473 K. In addition, a thermoelectric generator consisting of five legs of the 70%-Sb2Se3/30%-β-Cu2Se/PANI film is constructed and shown to provide an open-circuit voltage of 7.9 mV and an output power of 80.1 nW at ΔT = 30 K. This study demonstrates that the combination of inorganic thermoelectric materials and flexible polymers can generate power in wearable or portable devices.

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