A carbon nanotube field-emission X-ray tube with a stationary anode target

Sharma, Anjli; Kim, Ho Seob; Kim, Daewook; Ahn, Seungjoon

doi:10.1016/j.mee.2015.12.021

Cited by 10 publications

(5 citation statements)

References 15 publications

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“…Especially, instead of the tube current, the tube current density was investigated to compare performance of X-ray tubes because each X-ray tube has a different size or a geometry for application targets. Four kinds of electron emitters such as the CNT emitter using a free-standing CNT film (CNT film emitter), the tungsten filament emitter, the Si tip emitter, and the CNT paste emitter were selected. − ,,,− From comparison results, it is well understood that our cold cathode X-ray tube shows a much high tube current density at a small focal spot size. By the way, some X-ray tubes indicate a smaller focal spot size than our cold cathode X-ray tube but even though they show a relatively lower tube current. ,, Such kinds of X-ray tubes can be used for limited X-ray application systems like high-resolution X-ray microscopy or nondestructive analysis or medical mammography due to a small focal spot size.…”

Section: Resultsmentioning

confidence: 99%

High-Performance Cold Cathode X-ray Tubes Using a Carbon Nanotube Field Electron Emitter

Han

Lee

et al. 2022

ACS Nano

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A cold cathode X-ray tube was fabricated using a carbon nanotube (CNT) field electron emitter made by a free-standing CNT film which is composed of a highly packed CNT network. A lot of CNT bundles with a sharp tip are vertically aligned at the edge of the thin CNT film with a length of 10 mm and a thickness of 7 μm. The cold cathode X-ray tube using the CNT field emitter presents an extremely high tube current density of 152 A/cm2 (corresponding to tube current of 106.4 mA), the electron beam transmittance of 95.2% and a small focal spot size (FSS) of 0.5 mm. In addition, the cold cathode X-ray tube also shows stable lifetime during 100 000 shots. High emission current density of the cold cathode X-ray tube is mainly attributed to a lot of electron emission sites at an edge of the CNT film. The small FSS is caused by an ensemble of the CNT field electron emitter made by a free-standing thin CNT film and the optimized curve-shape elliptical focusing lens. Based on obtained results, the cold cathode X-ray tube can be widely used for various X-ray applications such as medical diagnosis systems and security check systems in the future.

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Section: Resultsmentioning

confidence: 99%

High-Performance Cold Cathode X-ray Tubes Using a Carbon Nanotube Field Electron Emitter

Han

Lee

et al. 2022

ACS Nano

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“…Due to the curvature present in the form of pentagons in CNTs , electrons are discharged from their tips [102]. The use of CNTs as electron emitters is associated with several advantages, which include stable field emission, high current densities over prolonged periods, low emission threshold potential, and long lifetime of the components for the construction of field emission devices [103].…”

Section: Carbon Nanotubes (Cnts) In Electronic Devicesmentioning

confidence: 99%

Synthesis, Properties, and Applications of Carbon Nanotubes: An Overview

Hussain,

Akbar,

Ahmad

et al. 2023

Sci Inquiry Rev.

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The current study attempts to review the literature concerning the synthesis, properties, and application of carbon nanotubes (CNTs). The methods used to produce carbon nanotubes include laser ablation, electric arc discharge, chemical vapor deposition, plasma-enhanced chemical vapor deposition, pulsed laser deposition, use of low-frequency ultrasound waves, heating a bulk polymer, and bulk sputtering. CNTs have excellent mechanical and thermal properties that strongly depend upon their structure. Functionalized magnetic CNTs are involved in magnetic force microscopy used in biomedicine. The liquid and plastic limit of kaolinite can be increased by adding CNTs to it. In the medical field, CNTs have numerous applications including gene delivery to cells, cancer therapy, drug delivery, and tissue regeneration. Their antioxidant nature also enables them to be used in cosmetic products and in the field of dermatology. They are also used to purify the environment, water, and in modern food-packaging technology. The sensors containing CNTs composite pellets are sensitive to gases, such as NH3, CO2, and CO H2O. CNTs are used to construct gas containers for hydrogen storage. They are also considered ideal for structural applications and their properties can be improved by making their composites with metals. Such metals may be introduced into the core of CNTs by different methods including solid-state reaction, arc-discharge method, and electrochemical techniques. The value of absorbed hydrogen gas in CNTs varies between 0.4 and 67 mass %. Recent advances encourage more research on CNTs to increase their clinical applications in the future.

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“…discusses several other field emission X‐ray tubes found throughout the literature with voltages ranging from 1.4 kV to 70 kV and tube currents ranging from 1.5 µA to 150 mA 1 . Following this 2015 review, other notable field emission X‐ray sources in the literature include a 21.5‐mm long, 80‐kV, 106.4 mA tube from Han et al., 3 a 50‐mm long, 50‐kV, 100‐mA source from Sharma et al., 18 and a 26.5‐mm long, 100‐kV, 4‐mA tube from Kato et al 19 . Of these three, the tube from Kato et al.…”

Section: Introductionmentioning

confidence: 96%

“…In their comprehensive review of CNT-based X-ray generation, Parmee et al discusses several other field emission X-ray tubes found throughout the literature with voltages ranging from 1.4 kV to 70 kV and tube currents ranging from 1.5 µA to 150 mA. 1 Following this 2015 review, other notable field emission X-ray sources in the literature include a 21.5-mm long, 80-kV, 106.4 mA tube from Han et al, 3 a 50-mm long, 50-kV, 100-mA source from Sharma et al, 18 and a 26.5-mm long, 100-kV, 4-mA tube from Kato et al 19 Of these three, the tube from Kato et al was designed for therapeutic dose delivery and was reported to achieve in-air dose rate measurements of 200 Gy/h (333 cGy/min) at 1 cm distance and 26 Gy/h (43 cGy/min) at 15 cm. Commercially, several sources are available such as Micro-X's 110-kV, 130-mA tube (as cited in Han et al 3 ), Golden Engineering, Inc.'s 150-kV, 0.5-mA (average current) source (as cited in Kato et al 19 ), and ETRI's 80-kV, 250-mA tube (as cited in Han et al 3 ).…”

Section: Introductionmentioning

confidence: 99%

Proof‐of‐concept for a thin conical X‐ray target optimized for intensity and directionality for use in a carbon nanotube‐based compact X‐ray tube

Insley,

Bartkoski,

Balter

et al. 2023

Medical Physics

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BackgroundCarbon nanotube‐based cold cathode technology has revolutionized the miniaturization of X‐ray tubes. However, current applications of these devices required optimization for large, uniform fields with low intensity.PurposeThis work investigated the feasibility and radiological characteristics of a novel conical X‐ray target optimized for high intensity and high directionality to be used in a compact X‐ray tube.MethodsThe proposed device uses an ultrathin, conical tungsten‐diamond target that exhibits significant heat loading while maintaining a small focal spot size and promoting forward‐directedness of the X‐ray field through preferential attenuation of oblique‐angled photons. The electrostatic and thermal properties of the theoretical tube were calculated and analyzed using COMSOL Multiphysics software. The production, transport, and calculation of radiological properties associated with the resultant X‐ray field were performed using the Geant4 toolkit via its wrapper, TOPAS.ResultsHeat transfer analysis of this X‐ray tube demonstrated the feasibility of a 200‐kV electron beam bombarding the proposed target at a maximum current of 100 mA using a 1‐ms symmetric duty cycle. The cathode of the X‐ray tube was designed to be segmented into nine switchable electrical segments for modulation of the focal spot size from 0.4‐ to 10.8‐mm. After importing the COMSOL‐derived electron beam into TOPAS for X‐ray production simulations, radiological analysis of the resultant field demonstrated high levels of intrinsic beam collimation while maintaining high intensity. A maximum dose rate of 17,887 cGy/min was calculated for 1‐mm depth in water at 7‐cm distance.ConclusionsThe proposed X‐ray tube design can create highly directional X‐ray fields with superior fluence compared to that of current commercial X‐ray tubes of comparable size.

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A carbon nanotube field-emission X-ray tube with a stationary anode target

Cited by 10 publications

References 15 publications

High-Performance Cold Cathode X-ray Tubes Using a Carbon Nanotube Field Electron Emitter

High-Performance Cold Cathode X-ray Tubes Using a Carbon Nanotube Field Electron Emitter

Synthesis, Properties, and Applications of Carbon Nanotubes: An Overview

Proof‐of‐concept for a thin conical X‐ray target optimized for intensity and directionality for use in a carbon nanotube‐based compact X‐ray tube

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