Vacuum tube amplifiers

Qiu, Jie; Levush, B.; Pasour, John; Katz, A.; Armstrong, C.M.; Whaley, D.R.; Tuček, J.; Kreischer, K.E.; Gallagher, D.

doi:10.1109/mmm.2009.934517

Cited by 118 publications

(45 citation statements)

References 39 publications

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“…[5,6] High aspect ratio carbon nanotubes (CNTs) revealed large field enhancement factor (generally larger than ≈10 3 ) and good field electron emission properties, [7][8][9] and have been used in field emission display (FED), [10,11] flat panel light source, [12] X-ray tube, [13,14] and microwave tube. [15,16] Semiconductor nanowires (e.g., ZnO, CuO) exhibited the field electron emission characteristics with low turn-on field and good uniformity, [17][18][19] and have been demonstrated to exhibit application prospect in flat panel X-ray source and detector.…”

Section: Doi: 101002/aelm201700295mentioning

confidence: 99%

An Analytical Modeling of Field Electron Emission for a Vertical Wedged Ordered Nanostructure

Shen

et al. 2017

Adv Elect Materials

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ties and potential applications: Spindt-type array composed of tapered microstructures have shown high current density over 1.6 × 10 3 A cm −2 with site density of 10 9 cm −2 , [2][3][4] and has been successfully applied in the traveling wave tube with the saturation power of 100 W and working frequency of 5 GHz. [5,6] High aspect ratio carbon nanotubes (CNTs) revealed large field enhancement factor (generally larger than ≈10 3 ) and good field electron emission properties, [7][8][9] and have been used in field emission display (FED), [10,11] flat panel light source, [12] X-ray tube, [13,14] and microwave tube. [15,16] Semiconductor nanowires (e.g., ZnO, CuO) exhibited the field electron emission characteristics with low turn-on field and good uniformity, [17][18][19] and have been demonstrated to exhibit application prospect in flat panel X-ray source and detector. [20,21] Although there is much experimental research and progress, theoretical analysis and calculation of field electron emission structure to tell people where the advantages lie and how to make improvements are still scarce, in order to obtain efficient field electron emission materials. Structural feature of materials affects some defining characteristics during the field electron emission process, including the field enhancement factor, local electronic field distribution, as well as actual emission sites and emission area. [22] And hence, it is of important significance to simulate and analyze the field emission structures and their corresponding emission properties. In this work, we focused on vertical tapered nanostructure and its derivative wedged ordered nanostructure. On the one hand, such nanostructures have the advantages that their sharp tips, large lengths, and vertical alignment help to bring large field enhancement factor and low turn-on field, [23,24] and their robust bottoms contribute to reducing the resistance and improving heat dissipation at high applied electric field. [25] On the other hand, these nanostructures could be obtained through existing preparation methods, whether top-down microprocessing or the bottom-up self-assembled growth. Table 1 lists the representative vertical tapered structural field emission materials and their derivatives. Majority of them have shown good field electron emission properties.Here, in order to develop a kind of field electron emission structure with high current density, vertical ordered tapered and wedged nanostructures have been analytically modeled and thoroughly studied. Local electrical field intensity and emission current density distributions have been simulated, and the The development of field electron emission materials requires purposeful analytical modeling of structural features. A vertical wedged ordered nanostructure shows better field emission current density because of its in-plane continuity at the top emission edge: Individually, its calculated average current density can be 8.3-26.7 times larger than a tapered nanostructure when its bottom area s increases from 0.5 to 2...

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Section: Doi: 101002/aelm201700295mentioning

confidence: 99%

An Analytical Modeling of Field Electron Emission for a Vertical Wedged Ordered Nanostructure

Shen

et al. 2017

Adv Elect Materials

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“…Note, influence of the wakefield dipole and quadrupole components on the source performance is nearly negligible due to short interaction length. Unlike mm-wave and sub-mm-wave tubes [13] and the dielectric-loaded slow-wave structure used in Ref. [10], the grating structure used in this experiment has exceptionally high group velocity, v gr ∼0.82c, where c is the speed of light.…”

Section: Radiator Assemblymentioning

confidence: 99%

Observation of a variable sub-THz radiation driven by a low energy electron beam from a thermionic rf electron gun

Smirnov

Agustsson

Berg

et al. 2015

Phys. Rev. ST Accel. Beams

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We report observations of an intense sub-THz radiation extracted from a ∼3 MeV electron beam with a flat transverse profile propagating between two parallel oversized copper gratings with side openings. Low-loss radiation outcoupling is accomplished using a horn antenna and a miniature permanent magnet separating sub-THz and electron beams. A tabletop experiment utilizes a radio frequency thermionic electron gun delivering a thousand momentum-chirped microbunches per macropulse and an alpha-magnet with a movable beam scraper producing sub-mm microbunches. The radiated energy of tens of microJoules per radio frequency macropulse is demonstrated. The frequency of the radiation peak was generated and tuned across two frequency ranges: (476-584) GHz with 7% instantaneous spectrum bandwidth, and (311-334) GHz with 38% instantaneous bandwidth. This prototype setup features a robust compact source of variable frequency, narrow bandwidth sub-THz pulses.

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“…Millimeter-wave radiation sources with high power, wide-bandwidth, and high efficiency are attractive for many applications, such as high-date-rate communications, high-resolution radar, and space applications [1][2][3][4][5][6][7][8]. Helix TWT is one of the most important millimeterwave vacuum amplifiers due to its outstanding combined performances in bandwidth, power capacity, and electronic efficiency.…”

Section: Introductionmentioning

confidence: 99%

A Novel Slotted Helix Slow-Wave Structure for Millimeter-Wave Traveling-Wave Tube

Liu¹,

Wei²,

Xu³

et al. 2013

PIER

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Abstract-A novel slotted helix slow-wave structure (SWS) is proposed to develop high power, wide-bandwidth, high reliability millimeter-wave traveling-wave tube (TWT). This structure, which can improve the heat dissipation capability of the helix SWS, evolves from conventional helix SWS with three parallel rows of rectangular slots made in the outside of the helix. In this paper, thermal stress analysis, the electromagnetic characteristics and the beam-wave interaction of this structure are investigated. The conclusions of this paper will be a great help for the design of millimeter-wave traveling-wave tube.

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Vacuum tube amplifiers

Cited by 118 publications

References 39 publications

An Analytical Modeling of Field Electron Emission for a Vertical Wedged Ordered Nanostructure

An Analytical Modeling of Field Electron Emission for a Vertical Wedged Ordered Nanostructure

Observation of a variable sub-THz radiation driven by a low energy electron beam from a thermionic rf electron gun

A Novel Slotted Helix Slow-Wave Structure for Millimeter-Wave Traveling-Wave Tube

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