100 W Operation of a Cold Cathode TWT

Fabrication of metallic double-gate field emitter arrays and their electron beam collimation characteristics

“…Research on field emitter arrays (FEAs) has been actively pursued [1][2][3][4][5][6][7][8][9][10][11][12][13] with the aim of realizing high current and high current density cathodes, e.g., for compact microwave vacuum electronic amplifiers, such as traveling wave tubes (TWTs) [14][15][16][17] and compact free electron lasers. 7,18 FEAs are expected to help simplify the gun design and extend the operation range of such TWTs.…”

“…7,18 FEAs are expected to help simplify the gun design and extend the operation range of such TWTs. 1,15 A recent report on a 5 GHz TWT using a single-gate Spindt FEA with 100 W output 17 demonstrates the practical feasibility of FEA-based TWTs. The possibility to generate high currents with densities above 10-100 A cm À2 (Ref.…”

Electron beam collimation with a 40 000 tip metallic double-gate field emitter array and in-situ control of nanotip sharpness distribution

“…The extremely high brightness of field emission electron beams has enabled the realization of electron microscopes with single-atom resolution 1 and has stimulated high current and high current density applications such as free-electron lasers 2,3 and THz vacuum electronic devices. [4][5][6][7] Field emitters can produce high brightness electron beams via quantum tunneling by applying a strong electric field in the order of GV/m to solid surfaces. Such fields can be created by a comparatively low potential with the help of the field enhancement at the nanometer-scale tip apexes.…”

Highly collimated electron beams from double-gate field emitter arrays with large collimation gate apertures

“…[1][2][3][4] Microwave vacuum electronic devices using single-gate FEAs, which allow for a compact and simplified gun design, have been successfully demonstrated. [5][6][7][8] However, a high current density field-emission electron beam with reduced transverse electron velocity spread is a crucial factor in extending the FEA-based vacuum electronic device technology to higher power densities and frequencies in the terahertz gap. 9,10 In double-gate FEAs, microfabricated field emitters are equipped with an electron extraction gate G ext and a collimation gate G col .…”

“…We note that I net falls to zero for V col beyond Ϫ69 V since the electrons are repelled by the potential field of G col and collected by G ext similarly to previous reports. [8][9][10][11][12][13][14][15][16] The increased current density at maximal collimation is due to the reduction of the emission angle depicted in 2. It is defined as the half width spread of the field-emission electron beam.…”