A5033548257- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Gyrotron and Vacuum Electronics Research
- Advanced X-ray Imaging Techniques
- Photocathodes and Microchannel Plates
- Laser Design and Applications
- Pulsed Power Technology Applications
- Plasma Diagnostics and Applications
- Laser-Matter Interactions and Applications
- Terahertz technology and applications
- Magnetic confinement fusion research
- Particle Detector Development and Performance
- Advanced Electron Microscopy Techniques and Applications
- Photonic and Optical Devices
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Laser-induced spectroscopy and plasma
- Radiation Detection and Scintillator Technologies
- Radiation Therapy and Dosimetry
- Photonic Crystals and Applications
- Integrated Circuits and Semiconductor Failure Analysis
- Crystallography and Radiation Phenomena
- Plasmonic and Surface Plasmon Research
- Electron and X-Ray Spectroscopy Techniques
University of California, Los Angeles
2015-2024
RadiaBeam Technologies (United States)
2012-2024
Astronomy and Space
2023
UCLA Health
2007-2022
Particle Beam Lasers (United States)
2012-2019
University of Chicago
2018
University of California System
2014-2017
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati
2010
Istituto Nazionale di Fisica Nucleare
2010
Brookhaven National Laboratory
2010
We experimentally investigate surface-plasmon assisted photoemission to enhance the efficiency of metallic photocathodes for high-brightness electron sources. A nanohole array-based copper surface was designed exhibit a plasmonic response at 800 nm, fabricated using focused ion beam milling technique, optically characterized and tested as photocathode in high power radio frequency photoinjector. Because larger absorption localization optical field intensity, charge yield observed under...
There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-metre (GeV m(-1)) gradients in order enable future generations both light sources and high-energy physics experiments. To address this need, short wavelength accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into accelerator structure or medium, are currently under investigation. One such wakefield accelerator, dielectric...
In the field of beam physics, two frontier topics have taken center stage due to their potential enable new approaches discovery in a wide swath science. These areas are: advanced, high gradient acceleration techniques, and x-ray free electron lasers (XFELs). Further, there is intense interest marriage these fields, with goal producing very compact XFEL. this context, recent advances radio-frequency cryogenic copper structure research opened door use surface electric fields between 250 500...
We report the observation of coherent Cerenkov radiation in terahertz regime emitted by a relativistic electron pulse train passing through dielectric lined cylindrical waveguide. describe beam manipulations and measurements involved repetitive creation including comb collimation nonlinear optics corrections. With this technique, modes beyond fundamental are selectively excited use appropriate frequency train. The spectral characterization structure shows preferential excitation higher...
We report first evidence of wakefield acceleration a relativistic electron beam in dielectric-lined slab-symmetric structure. The high energy tail $\ensuremath{\sim}60\text{ }\text{ }\mathrm{MeV}$ was accelerated by $\ensuremath{\sim}150\text{ }\mathrm{keV}$ 2 cm-long, ${\mathrm{SiO}}_{2}$ waveguide, with the or deceleration clearly visible due to use bifurcated longitudinal distribution that serves approximate driver-witness pair. This split-bunch is verified reconstruction analysis emitted...
Plasma wakefields can enable very high accelerating gradients for frontier energy particle accelerators, in excess of 10 GeV/m. To overcome limits on total acceleration achievable, specially shaped drive beams be used both linear and nonlinear plasma wakefield accelerators (PWFA), to increase the transformer ratio, implying that beam deceleration is minimized relative obtained wake. In this Letter, we report results a PWFA, ratio experiment using high-charge, longitudinally asymmetric cell....
We examine the use of sextupole magnets to correct nonlinearities in longitudinal phase space transformation a relativistic beam charged particles dispersionless translating section, or dogleg. Through heuristic analytical arguments and examples derived from recent experimental efforts, augmented by simulations using particle tracking codes PARMELA ELEGANT, corrections are found be effective optimizing such structures for compression shaping current profile beam, manipulation second-order...
Photonic structures operating in the terahertz (THz) spectral region enable essential characteristics of confinement, modal control, and electric field shielding for very high gradient accelerators based on wakefields dielectrics. We report here an experimental investigation THz wakefield modes a three-dimensional photonic woodpile structure. Selective control exciting or suppressing with nonzero transverse wave vector is demonstrated by using drive beams varying ellipticity. Additionally,...
Temporal pulse tailoring of charged-particle beams is essential to optimize efficiency in collinear wakefield acceleration schemes. In this Letter, we demonstrate a novel phase space manipulation method that employs beam interaction dielectric structure, followed by bunch compression permanent magnet chicane, longitudinally tailor the shape an electron beam. This compact, passive, approach was used generate nearly linearly ramped current profile relativistic experiment carried out at...
We report experimental measurements of narrow-band, single-mode excitation, and drive beam energy modulation, in a dielectric wakefield accelerating structure with planar geometry Bragg-reflector boundaries. A short, relativistic electron ($\ensuremath{\sim}1\text{ }\text{ }\mathrm{ps}$) moderate charge ($\ensuremath{\sim}100\text{ }\mathrm{pC}$) is used to the wakefields structure. The fundamental mode reinforced by constructive interference alternating layers at boundary, characterized...
In this paper, we discuss the velocity compression in a short rf linac of an electron bunch from photoinjector operated blowout regime. Particle tracking simulations shows that with beam charge 2 pC ultrashort duration 16 fs can be obtained at tight longitudinal focus downstream linac. A simplified coherent transition radiation (CTR) spectrum method is developed to enable measurement (sub-50 fs) bunches low energy (5 MeV) and charges (<10 pC). method, ratio selected by two narrow bandwidth...
An intense, subpicosecond, relativistic electron beam traversing a dielectric-lined waveguide generates very large amplitude electric fields at terahertz (THz) frequencies through the wakefield mechanism. In recent work employing this technique to accelerate charged particles, generation of high-power, narrow-band THz radiation was demonstrated. The radiated waves contain with measured exceeding $2\text{ }\text{ }\mathrm{GV}/\mathrm{m}$, orders magnitude greater than those available by other...
The recently demonstrated concept of the plasma photocathode, whereby a high-brightness bunch is initialized by laser ionization within wakefield acceleration bubble, informally referred to as Trojan Horse acceleration. In similar vein, dielectric incorporates dielectric-lined waveguide support charged particle beam-driven accelerating mode and uses initiated neutral gas generate witness beam. One advantages reduced requirements in terms timing precision due operation at lower frequency....
Relativistic charged-particle beams that generate intense longitudinal fields in accelerating structures also inherently couple to transverse modes. The effects of this coupling may lead beam breakup instability and thus must be countered preserve quality applications such as linear colliders. Beams with highly asymmetric sizes (flat beams) have been shown suppress the initial slab-symmetric structures. However, modes remains, solution serves only delay instability. In order understand...
Wakefield based accelerators capable of accelerating gradients 2 orders magnitude higher than present offer a path to compact high energy physics instruments and light sources. However, for gradient accelerators, beam instabilities driven by commensurately transverse wakefields limit quality. Previously, it has been theoretically shown that can be reduced elliptically shaping the sizes beams in dielectric structures with planar symmetry. Here, we report experimental measurements demonstrate...
It has long been noted that the nonlinear "blowout" regime of PWFA certain critical aspects for producing high quality beams are owed to elimination electron density and current inside beam‐occupied region: time‐independent, linear ion‐focusing, acceleration independent transverse position. Unfortunately, in applying this scheme a collider, efficiency considerations strongly encourage use pulse trains, which one superimposes wakes driving accelerating turn. This implies needs maintain stable...
Spiking electron beam driven plasma waves with novel laser-driven underdense photocathodes can produce witness bunches extreme brightness. The development of such hybrid systems and their potential as future plasma-based accelerators compact yet high performance light sources is discussed.
The suppression of transverse wakefield effects using transversely elliptical drive beams in a planar structure is studied with simple analytical model that unveils the geometric nature this phenomenon. By analyzing suggested we derive scaling laws for amplitude longitudinal and wake potentials as function Gaussian beam ellipticity---${\ensuremath{\sigma}}_{x}/a$. We explicitly show accelerator application it beneficial to use highly mitigating forces while maintaining accelerating field....
An overview on the underlying principles of hybrid plasma wakefield acceleration scheme dubbed "Trojan Horse" is given. The concept based laser-controlled release electrons directly into a particle-beam-driven blowout, paving way for controlled, shapeable electron bunches with ultralow emittance and ultrahigh brightness. Combining virtues low-ionization-threshold underdense photocathode GV/m-scale electric fields practically dephasing-free beam-driven this constitutes 4th generation scheme....