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Advances in electron beam technology have been central to creating the current generation of x-ray free electron lasers and ultra-fast electron microscopes. These once exotic devices have become essential tools for basic research and…

Accelerator Physics · Physics 2016-11-29 David H. Dowell

A common issue encountered in photoemission electron sources used in electron accelerators is the transverse inhomogeneity of the laser distribution resulting from the laser-amplification process and often use of frequency up conversion in…

Accelerator Physics · Physics 2017-11-22 A. Halavanau , G. Qiang , G. Ha , E. Wisniewski , P. Piot , J. G. Power , W. Gai

Experimental observations of thermionic electron emission demonstrate a smooth transition between TL and FSCL regions of the emitted-current-density-versus-temperature (J-T) (Miram) curve and the emitted-current-density-versus-voltage (J-V)…

High peak and average power free-electron lasers (FELs) in the terahertz region (THz) require small diameter, low-emittance, and high voltage electron beams. This paper presents two 1.5-2 MV, 100-200 A, thermionic cathode electron source…

Accelerator Physics · Physics 2024-03-22 Richard B. True , Henry P. Freund , Michael V. Fazio , Patrick G. O'Shea

Broader adoption of 4D ultrafast electron microscopy (UEM) for the study of chemical, materials, and quantum systems is being driven by development of new instruments as well as continuous improvement and characterization of existing…

Applied Physics · Physics 2025-01-15 Simon A. Willis , David J. Flannigan

Electron transpiration cooling (ETC) can reduce aerothermal loads on sharp hypersonic leading edges, but its performance is governed by whether thermionically emitted electrons escape the hot surface or return as cathode-directed backflow.…

Plasma Physics · Physics 2026-05-11 Wushun Zhang , Weixing Zhou , Yinjian Zhao

A FEM application for the accurate design of composite backing of ultrasonic transducers is presented. The idea is to obtain the dependence between the volume ratio of the tungsten powder in an epoxy matrix used as a backing and the final…

Computational Physics · Physics 2022-03-17 Eduardo Moreno , Wagner C. A. Pereira , Marco Antonio von Kruger , Lorenzo Leija , Antonio Ramos

A new type of field emission display(FED) based on an edge-enhance electron emission from metal-insulator-semiconductor (MIS) thin film structure is proposed. The electrons produced by an avalanche breakdown in the semiconductor near the…

Instrumentation and Detectors · Physics 2009-10-31 V. N. Konopsky

Fluorescent atomic defects, especially in dielectric materials, such as diamond are quite promising for several emerging quantum applications. However, efficient light extraction, directional emission, and narrow spectral emission are key…

We are proposing a novel fabrication method for single crystal diamond scanning probes, exploiting the method of Faraday cage angled etching (FCAE). Electron-beam lithography (EBL) and inductively coupled plasma (ICP) etching as…

Quantum Physics · Physics 2021-04-13 C. Giese , P. Quellmalz , P. Knittel

A common issue encountered in photoemission electron sources used in electron accelerators is distortion of the laser spot due to non ideal conditions at all stages of the amplification. Such a laser spot at the cathode may produce…

Accelerator Physics · Physics 2016-09-07 A. Halavanau , G. Ha , G. Qiang , W. Gai , J. Power , P. Piot , E. Wisniewski , D. Edstrom , J. Ruan , J. Santucci

Large area carbon nanotube (CNT) cathodes made from yarns, films or fibers have long been promising as next generation electron sources for high power radio frequency (rf) and microwave vacuum electronic devices. However, experimental…

Applied Physics · Physics 2023-01-18 Taha Y. Posos , Sergey V. Baryshev

Five parameters of a model of a polymer electrolyte membrane fuel cell cathode (the porosity of the gas diffusion layer, the porosity of the catalyst layer, the exchange current density of the oxygen reduction reaction, the effective ionic…

Materials Science · Physics 2013-08-22 Qingzhi Guo , Vijay A. Sethuraman , Ralph E. White

Charge-coupled device (CCD), along with the complementary metal-oxide-semiconductor (CMOS), is one of the major imaging technologies. Traditional CCDs rely on the charge transfer between potential wells, which gives them advantages of…

Nitrogen incorporated ultrananocrystalline diamond ((N)UNCD) could be an enabling material platform for photocathode applications due to its high emissivity. While the quantum efficiency (QE) of UNCD was reported by many groups, no…

We report on the growth and characterization of a new class of photocathode structures for application as electron sources to produce high brightness electron beams for accelerator applications. The sources are realized using III-Nitride…

Accelerator Physics · Physics 2022-04-06 L. Cultrera , E. Rocco , F. Shahedipour-Sandvik , L. D. Bell , J. K. Bae , I. V. Bazarov , P. Saha , S. Karkare , A. Arjunan

Two-dimensional (2D) materials are particularly attractive to build the channel of next-generation field-effect transistors (FETs) with gate lengths below 10-15 nm. Because the 2D technology has not yet reached the same level of maturity as…

Mesoscale and Nanoscale Physics · Physics 2023-10-30 Mathieu Luisier , Cedric Klinkert , Sara Fiore , Jonathan Backman , Youseung Lee , Christian Stieger , Áron Szabó

Cathodoluminescence has attracted interest in scanning transmission electron microscopy since the advent of commercial available detection systems with high efficiency, like the Gatan Vulcan or the Attolight M\"onch system. In this work we…

Reported here is the first demonstration of electron beam generation in an SRF TESLA 1.3 GHz gun equipped with field emission cathode when operated at 2 Kelvin. The cathode is submicron film of nitrogen-incorporated ultrananocrystalline…

Evanescent waves are central to many technologies such as near-field imaging that beats the diffraction limit and plasmonic devices. Frustrated total internal reflection (FTIR) is an experimental method commonly used to study evanescent…