C-5 Miniature X-ray Tubes Utilizing Carbon Nanotube-Based Cold Cathodes

Reyes-Mena, A.; Turner, D. Clark; Bard, E.; Jensen, C.; Qiu, Qingdong; Gao, Bo; Lü, Jianyun; Zhou, Otto

doi:10.1154/1.1779867

Cited by 16 publications

(26 citation statements)

References 10 publications

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“…Clearly, the nature of devices developed for research and design iteration, this is the sensible choice. However some improvements -for example, miniaturisation -have seen the development of a sealed construction [150,154,197,198]. Table 1 below summarises the cumulative literature to-date on the progress towards the realisation of a functionally enhanced CNT-based FE X-ray source.…”

Section: Demountable Tubesmentioning

confidence: 99%

“…Most devices fabricated to date operate in either DC or low frequency (tens of Hz) mode [148,150,151,154,160,163,169,171,182,184,159,200,202,204,205,[207][208][209]211,212] with only a very limited set of electronically controlled devices operating at frequencies in excess of a few hundred Hz to a few kHz [149,198,203,210]. The highest electronic pulse rate achieved to date is of the order of 10 7 Hz, as reported by Cheng et al [201].…”

Section: Pulsed Sourcesmentioning

confidence: 99%

“…Nevertheless, the pulse rate achieved by Thales [233] in their optically gated devices exceeds all other devices by a significant margin. Figure 6(a) shows the anode current and X-ray intensity temporal response by Reyes-Mena et al [198]. Here the X-ray beam 0-90% turn-on time is <50 μs and the system is used to image a rotating cooling fan.…”

Section: Pulsed Sourcesmentioning

confidence: 99%

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X-ray generation using carbon nanotubes

et al. 2015

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Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications, there have been few fundamental technological advances. However, with the emergence of ever more demanding medical and inspection techniques, including computed tomography and tomosynthesis, security inspection, high throughput manufacturing and radiotherapy, has resulted in a considerable level of interest in the development of new fabrication methods. The use of conventional thermionic sources is limited by their slow temporal response and large physical size. In response, field electron emission has emerged as a promising alternative means of deriving a highly controllable electron beam of a well-defined distribution. When coupled to the burgeoning field of nanomaterials, and in particular, carbon nanotubes, such systems present a unique technological opportunity. This review provides a summary of the current state-of-the-art in carbon nanotube-based field emission X-ray sources. We detail the various fabrication techniques and functional advantages associated with their use, including the ability to produce ever smaller electron beam assembles, shaped cathodes, enhanced temporal stability and emergent fast-switching pulsed sources. We conclude with an overview of some of the commercial progress made towards the realisation of an innovative and disruptive technology.

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Section: Demountable Tubesmentioning

confidence: 99%

Section: Pulsed Sourcesmentioning

confidence: 99%

Section: Pulsed Sourcesmentioning

confidence: 99%

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X-ray generation using carbon nanotubes

et al. 2015

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“…Поэтому не удивительно, что в 1995 г. появилось несколько работ, в которых описыва-лось явление полевой эмиссии из УНТ [2][3][4]. Это явле-ние легло в основу ряда важных с точки зрения практики применений: плоских экранов мониторов [5,6], миниа-тюрных рентгеновских трубок [7,8], светоизлучающих устройств [9,10], миниатюрных вакуумных ламп [11,12], усилителей терагерцового диапазона [13,14], высокоча-стотных вакуумных переключателей [15].…”

Section: Introductionunclassified

Стабильность Полевой Эмиссии Одиночной Углеродной Нанотрубки

Булярский¹,

Дудин²,

Лакалин³

et al. 2018

Журнал Технической Физики

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Экспериментально наблюдался разогрев одиночной многостенной углеродной нанотрубки при протекании через нее тока полевой эмиссии и появление термоэмиссионной составляющей. Нагрев нанотрубки при протекании тока происходит в результате выделения джоулевой теплоты на ее последовательном сопротивлении. Из решения уравнения теплопроводности была сделана оценка величины температуры перегрева эмитирующего конца. Установлены условия устойчивости полевой эмиссии и возникновения термополевой эмиссии. где t(y) = 1 + 0.1107y 1.33 , θ(y) = 1 − y 1.69 , y = e ϕ eE 4πε 0 , e -элементарный заряд (C), m --масса свободного электрона (kg), h -постоянная Планка (Js), ε 0 -электрическая постоянная (F/m), E -напряженность локального электрического поля вблизи эмитирующей поверхности (V/m), ϕ -работа выхода электрона (J), J -плотность тока ПЭ (A/m 2 ), t(y) и θ(y) -слабо изменяющиеся функции, которые при сопоставлении формулы (1) с экспериментальными данными могут быть приняты равными единице без увеличения погреш-ности в определении работы выхода. Если пренебречь слабой степенной зависимостью функций t(y) и θ(y), положив t(y) ≈ 1 и θ(y) ≈ 1, то после подстановки всех констант и перевода работы выхода в eV получается выражениеУже в первых работах, посвященных изучению явле-ния полевой эмиссии, было обнаружено, что конец нано-трубки разогревается в процессе протекания эмиссион-ного тока, а его температура пропорциональна квадрату плотности тока [19,21], что находится в соответствии с законом Джоуля-Ленца. Разогрев конца нанотрубки ве-дет к появлению токов термоэлектронной эмиссии (ТЭ), которые могут быть большими при высоких плотностях тока и даже превосходить токи полевой эмиссии. Кроме 920

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“…그러나 최근에는 이러한 X선 튜 브를 작게 제작하여 다양한 부위에 적용하고자 기술 이 보고되고 있다 [2] . 표 1은 이러한 초소형 X선 튜브 의 개발 현황을 요약한 것이다 [2][3][4][5][6][7] . 이러한 초소형 X선 …”

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Feasibility study of insertable miniature x-ray source for dental imaging

Cho¹,

Kim²,

An³

et al. 2012

Journal of the Korean Society of Radiology

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Conventional periphery radiography system has a various problem such as patient dose and the pain of X-ray examination. In this paper, to solve these problems, we suggested insertional miniature x-ray system and we verified the feasibility of this system. First, we performed the Geant4 x-ray simulation to design x-ray collimator and filter to use miniature x-ray tube and we decided optimized thickness of filter and collimator. Also, we measured x-ray spectrum using CdTe detector and PX4 module to verify simulation results. Also, we acquired teeth image of fabricated phantom using conventional dental x-ray and prosed miniature x-ray system. As a results, our system has good image quality as compared to those of conventional systems. Our evaluation of the proposed system indicates that it can be potentially very useful for dental imaging.

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C-5 Miniature X-ray Tubes Utilizing Carbon Nanotube-Based Cold Cathodes

Cited by 16 publications

References 10 publications

X-ray generation using carbon nanotubes

X-ray generation using carbon nanotubes

Стабильность Полевой Эмиссии Одиночной Углеродной Нанотрубки

Feasibility study of insertable miniature x-ray source for dental imaging

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