Efforts by a number of institutions to develop Dielectric-Loaded Accelerating (DLA) structure capable supporting high gradient acceleration when driven an external radio frequency source have been ongoing over the past decade. Single surface resonant multipactor has previously identified as one major limitations on practical application DLA structures in electron accelerators. In this paper, we report results experiment that demonstrated suppression growth X-band through use applied axial...

We have measured an intense THz radiation produced by a sub-picosecond, relativistic electron bunch in dielectric loaded waveguide. For efficient pulse extraction, the waveguide end was cut at angle. appropriate choice of angle cut, such antenna converts TM01 mode excited into free-space fundamental Gauss-Hermite propagating with respect to beam trajectory. Simulations show that more than 95% energy can be extracted using simple approach. More 40 oscillations about 170 ps long 0.48 signal...

We analyze radiation produced by an ultrarelativistic charge as it exits the open end of a cylindrical waveguide with dielectric lining. The can be either orthogonal to structure axis or skewed. To obtain terahertz from waveguides centimeter millimeter radii, we consider high order TM(0m) modes driven beam. integral representation which describes single mode in Fraunhofer zone. perform series numerical calculations for structures look promising generation THz radiation. It is shown that...

The fabrication and performance evaluation of single-crystal diamond refractive X-ray lenses which the surfaces are paraboloids revolution for focusing X-rays in two dimensions simultaneously reported. were manufactured using a femtosecond laser micromachining process tested synchrotron radiation. Such stacked together to form standard compound lens (CRL). Owing superior physical properties material, CRLs could become indispensable wavefront-preserving primary optics free-electron lasers...

High-quality bi-concave 2D focusing diamond X-ray lenses of apex-radius R = 100 µm produced via laser-ablation and improved mechanical polishing are presented here. Both for polished unpolished individual stacks ten lenses, the remaining figure errors determined using speckle tracking shown these results compared with those commercial 50 beryllium that have similar strength physical aperture. For two (polished unpolished) a stack eleven this paper presents measured beam profiles out focus...

Metamaterials (MTMs) are artificial structures made of periodic elements and designed to obtain specific electromagnetic properties. As long as the periodicity size much smaller than wavelength interest, an structure can be assigned a permittivity permeability, just like natural materials. customized have permeability desired for particular application. When simultaneously negative in some frequency range, metamaterial is called double-negative or left-handed has unusual For example,...

Fabrication and results of high-resolution X-ray topography characterization diamond single-crystal plates with large surface area (10 mm × 10 mm) (111) crystal orientation for applications in high-heat-load optics are reported. The were fabricated by laser-cutting the facets crystals grown using high-pressure high-temperature methods. intrinsic quality a selected 3 7 region one studied samples was found to be suitable wavefront-preserving optics. Wavefront performed sequential diffraction...

Quantum efficiency (QE), intrinsic emittance, and robustness are the three most important figures of merit for photocathodes, first two determine ultimate achievable brightness an electron beam, third one directly correlates with complications a beamline design. Nitrogen-incorporated ultrananocrystalline diamond [(N)UNCD] materials promising candidates photocathode applications due to their remarkable emission performance as well moderate vacuum requirement. Two (N)UNCD photocathodes have...

The complete design, fabrication, and performance evaluation of a compact, single cell, $X$-band ($\sim$9 GHz) electron injector based on field emission cathode (FEC) are presented. A pulsed beam is generated by 10's kW radiofrequency (RF) magnetron signal from plug-in thin film nitrogen-incorporated ultrananocrystalline diamond (N)UNCD FEC cartridge. Testing the with was conducted in beamline equipped solenoid, Faraday cup imaging screen. results show that typically cartridge produces...

We consider the mode transformation in a circular waveguide with transverse boundary between vacuum part and cylindrical dielectric layer channel. Two situations are analyzed: an incident is launched on from of or one. The assumed to be both propagating evanescent. Analysis performed using decomposition technique. Approximate solutions obtained for cases narrow channel case thin layer. A numerical algorithm calculating at arbitrary radius developed. Typical dependences reflection...

This paper is devoted to the analysis of electromagnetic field excited by a charge moving in circular waveguide, which consists two semi-infinite parts. The moves with constant velocity along waveguide axis from partially dielectric section into homogeneous one. It assumed that Cherenkov radiation generated bilayer section. total represented as sum known forced infinite regular and free resulting presence transverse boundary. system algebraic equations for amplitudes free-field modes...

Diamond is an excellent material for dielectric loaded accelerating structures. It has a high breakdown threshold, very low losses and extremely coefficient of thermal conductance. In this paper we review progress on the design development diamond—based structures in GHz—THz frequency range.

Diamond field-emitter arrays (DFEAs) are of diamond pyramids with exquisitely sharp tips and micrometerscale bases that produce high current densities. These can be fabricated in arbitrary shapes, ranging from single to many millions tips, so they an inherently shaped electron beam. Each tip emits a modest current, but the large dense array Amps. We investigating these cathodes for use dielectric wakefield accelerators; however, may also applicable vacuum microwave tubes. Recently, beam...

Abstract We report on the realization of an extremely sensitive x-ray polarization microscope, allowing to detect tiniest changes 1 in 100 billion (10 −11 ) with a μ m-size focused beam. The extreme degree purity places most stringent requirements orientation polarizer and analyzer crystals as well composition form fidelity lenses, which must not exhibit any birefringence. results show that these are currently only met by polymer lenses. Highly scanning microscopy thus is established new...

Metamaterials (MTM) are artificial periodic structures made of small elements and designed to obtain specific electromagnetic properties. As long as the periodicity size much smaller than wavelength interest, an structure can be described by a permittivity permeability, just like natural materials. customized have permeability desired for particular application. Waveguides loaded with metamaterials interest because change dispersion relation waveguide significantly. Slow backward waves,...

Measurement of Cherenkov radiation (CR) has long been a useful technique for charged particle detection and beam diagnostics. We are investigating metamaterials engineered to have refractive indices tailored enhance properties CR that detectors cannot be obtained using conventional media. in dispersive media with large index differs significantly from the same effect detector media, like gases or aerogel. The pattern presents lobes at very angles respect motion. Moreover, frequency velocity...

In this paper we report on generation of a 450 GHz signal in corrugated metallic structure by short electron beam. The measurement was done at the Accelerator Test Facility Brookhaven National Laboratory. experiment generated 50kW peak power with 10-15% bandwidth. We also observed energy modulation long, energy-chirped beam passing through structure.

An electrical response of a diffracting diamond (111) crystal was studied in single electrode configuration where the deposited on small portion entrance surface. The experiment performed ambient air using an x-ray beam after Si double-crystal monochromator with set Bragg diffraction condition. It found that electric current as function angle exhibits behavior characteristic secondary yield curves (e.g.,¹). is proposed to utilize this effect monitor intensity reflected beam. Such...

We present fabrication and characterization of ultra-thin with ∼15-25 µm thick (300 in diameter) diamond single-crystal membranes for various applications synchrotron radiation sources, x-ray free-electron lasers (XFELs), XFEL oscillators. Ultra-thin are fabricated using laser ablation techniques ultra-short (femtosecond) pulses. Here, we report optimizing the parameters such as fluence, power, repetition rate, pulse length, wavelengths. The crystal quality has been characterized by rocking...

We propose open-side resonators for THz gyrotrons. These could be based on metallic radial Bragg reflectors short pulse devices driven by high-voltage beams or diamond CW operation. Resonators of both types can produced using femtosecond laser ablation technology developed in Euclid Techlabs LLC.

We consider three types of THz accelerating structures. The structures the first type operate with relatively long pulses having narrow bandwidth. These are assumed to be fed by radiation produced high-power rf sources like gyrotrons or drive electron beam. mentioned exploit Bragg principles, in order provide high shunt impedance as well necessary mode selection. dielectric this could a femtosecond laser ablation system developed at Euclid Techlabs. This technology had already been tested...