A5050314577- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Gyrotron and Vacuum Electronics Research
- Advanced X-ray Imaging Techniques
- Laser-Plasma Interactions and Diagnostics
- Superconducting Materials and Applications
- Electromagnetic Simulation and Numerical Methods
- Laser-Matter Interactions and Applications
- Electron and X-Ray Spectroscopy Techniques
- Experimental and Theoretical Physics Studies
- Photocathodes and Microchannel Plates
- Electromagnetic Compatibility and Measurements
- Crystallography and Radiation Phenomena
- Near-Field Optical Microscopy
- Quantum and Classical Electrodynamics
- Advancements in Photolithography Techniques
- Pulsed Power Technology Applications
- Laser Design and Applications
- Terahertz technology and applications
- Particle Detector Development and Performance
- Microwave and Dielectric Measurement Techniques
- Advanced Electron Microscopy Techniques and Applications
- Electromagnetic Scattering and Analysis
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
SLAC National Accelerator Laboratory
2014-2023
Stanford University
2008-2022
Brookhaven National Laboratory
2016-2022
Thomas Jefferson National Accelerator Facility
2021
Menlo School
2004-2016
Euclid Techlabs (United States)
2016
Office of Basic Energy Sciences
2016
Office of Science
2016
Budker Institute of Nuclear Physics
2016
Siberian Branch of the Russian Academy of Sciences
2016
We propose to use the mechanism of an echo effect previously observed in hadron accelerators for up-frequency conversion density modulation electron beam. show that, generation high harmonics, this method is much more efficient comparison with currently used approach. A one-dimensional model developed which allows us optimize amplitude a given harmonic number.
We propose a novel method to generate femtosecond and subfemtosecond photon pulses in free-electron laser by selectively spoiling the transverse emittance of electron beam. Its merits are simplicity ease implementation. When system is applied Linac Coherent Light Source, it can provide x-ray order 1 fs duration containing about ${10}^{10}$ transversely coherent photons.
A microbunching instability driven by longitudinal space charge, coherent synchrotron radiation, and linac wakefields is studied for the light source (LCLS) accelerator system. Since uncorrelated (local) energy spread of electron beams generated from a photocathode rf gun very small, gain may be large enough to significantly amplify rf-gun modulations or even shot-noise fluctuations beam. The can increased an order magnitude provide strong Landau damping against without degrading...
In this paper, we systematically study the echo-enabled harmonic generation (EEHG) free electron laser (FEL). The EEHG FEL uses two modulators in combination with dispersion sections that allow one to generate beam a high density modulation starting relatively small initial energy of beam. After presenting an analytical theory phenomenon, address several practically important issues, such as effect incoherent synchrotron radiation sections, and transverse size modulator. Using representative...
The effect of an artificially enhanced rough surface on the secondary electron yield (SEY) was investigated both theoretically and experimentally. Analytical studies triangular rectangular grooved surfaces show connection between characteristic parameters a given geometry to SEY reduction. strong magnetic field is also discussed. samples have been measured results agree with particle simulations using Monte Carlo approach.
The very bright electron beam required for an x-ray free-electron laser (FEL), such as the linac coherent light source (LCLS), is susceptible to a microbunching instability in magnetic bunch compressors, prior FEL undulator. uncorrelated energy spread LCLS can be increased by order of magnitude provide strong Landau damping against without degrading performance. To this end, ``laser-heater'' system has been installed injector, which modulates 135-MeV with IR-laser short undulator, enclosed...
We report the first experimental demonstration of echo-enabled harmonic generation technique, which holds great promise for high-power, fully coherent short-wavelength radiation. In this experiment, radiation at 3rd and 4th harmonics second seed laser is generated from so-called beam echo effect. The experiment confirms physics behind technique paves way applying seeded x-ray free electron lasers.
Accelerator-based light sources such as storage rings and free-electron lasers use relativistic electron beams to produce intense radiation over a wide spectral range for fundamental research in physics, chemistry, materials science, biology medicine. More than dozen operate worldwide, new are being built deliver that meets with the ever increasing sophistication depth of research. Even so, conventional accelerator techniques often cannot keep pace demands and, thus, approaches continue...
A novel approach for the generation of ultrabright attosecond electron bunches is proposed, based on acceleration in vacuum, by a short laser pulse. The laser-pulse profile tailored such that electrons are both focused and accelerated ponderomotive force light. Using time-averaged equations motion, analytical criteria optimal regime found. It shown realistic parameters, beam with up to 10(6) particles normalized transverse longitudinal emittances <10(-8) m can be produced.
The coherent synchrotron radiation of a bunch in compressor may lead to the microwave instability producing longitudinal modulation with wavelengths small compared length. It can also be source an undesirable emittance growth compressor. We derive and analyze equation that describes linear evolution taking into account incoherent energy spread finite beam. Numerical solution this for Linac Coherent Light Source gives amplification factor different beam microbunching.
The first experimental study is presented of a corrugated wall device that uses wakefields to remove linear energy correlation in relativistic electron beam (a ``dechirper''). Time-resolved measurements both longitudinal and transverse the are compared with simulations. This demonstrates feasibility employ dechirper for precise control phase space next generation free-electron-lasers.
A relativistic electron beam moving in a circular orbit free space can radiate coherently if the wavelength of synchrotron radiation exceeds length bunch. In accelerators coherent bunch is usually suppressed by shielding effect conducting walls vacuum chamber. However an initial density fluctuation with characteristic much shorter than coherently. If reaction force results growth fluctuation, one expect instability which leads to microbunching and increased at short wavelengths. Such studied...
We propose a scheme that combines the echo-enabled harmonic generation technique with bunch compression and allows one to generate numbers of few hundred in microbunched beam through up-conversion frequency an ultraviolet seed laser. A few-cycle intense laser is used required energy chirp for selection attosecond x-ray pulse. Sending this short undulator results isolated Using representative realistic set parameters, we show 1 nm pulse peak power MW duration as 20 attoseconds (FWHM) can be...
Echo-enabled harmonic generation free electron lasers hold great promise for the of fully coherent radiation in x-ray wavelengths. Here we report first evidence high harmonics from echo-enabled technique realistic scenario where laser energy modulation is comparable to beam slice spread. In this experiment, at seventh second seed generated when amplitude about 2-3 times The experiment confirms underlying physics and may have a strong impact on emerging seeded that are capable generating...
This paper discusses the extension to different electron beam aspect ratio of Child-Langmuir law for maximum achievable current density in guns. Using a simple model, we derive quantitative formulas good agreement with simulation codes. The new scaling laws peak temporally long and transversely narrow initial distributions can be used estimate brightness suggest paths injector optimization.
Harmonic seeding of free electron lasers has attracted significant attention as a method for producing transform-limited pulses in the soft x-ray region. multiplication schemes extend to shorter wavelengths, but also amplify spectral phase errors initial seed laser, and may degrade pulse quality impede production pulses. In this paper we consider effect laser high gain harmonic generation echo-enabled generation. We use simulations confirm analytical results case linearly chirped lasers,...
High quality electron beams with flat distributions in both energy and current are critical for many accelerator-based scientific facilities such as free-electron lasers MeV ultrafast diffraction microscopes. In this Letter, we report on using corrugated structures to compensate the beam nonlinear chirp imprinted by curvature of radio-frequency field, leading a significant reduction spread. By pair orthogonal orientations, show that quadrupole wakefields, which, otherwise, increase...
We propose and analyze a scheme to generate enhanced narrow-band terahertz (THz) radiation through down-conversion of the frequency optical lasers using laser-modulated electron beams. In beam is first energy modulated by two with wave numbers ${k}_{1}$ ${k}_{2}$, respectively. After passing dispersion section, modulation converted density modulation. Because nonlinear conversion process, will have at number $k=n{k}_{1}+m{k}_{2}$, where $n$ $m$ are positive or negative integers. By properly...
Electron beam energy chirp is an important parameter that affects the bandwidth and performance of a linac-based, free-electron laser. In this paper we study wakefields generated by passing between flat metallic plates with small corrugations, then apply such device as passive dechirper for Linac Coherent Light Source (LCLS) control multi-GeV femtosecond electron beam. Similar devices have been tested in several places at relatively low energies ($\ensuremath{\sim}100\text{ }\mathrm{MeV}$)...
In order to reach the high peak current required for an x-ray free electron laser, two separate magnetic dipole chicanes are used in Linac Coherent Light Source accelerator compress bunch length stages. these compressors, coherent synchrotron radiation (CSR) can be emitted either by a short or any longitudinal density modulation that may on bunch. this paper, we report detailed measurements of CSR-induced energy loss and transverse emittance growth compressors. Good agreement is found...
We use a Vlasov-Fokker-Planck program and linearized Vlasov solver to study the microwave instability threshold of impedance models: (1) $Q=1$ resonator (2) shielded coherent synchrotron radiation (CSR), find results two programs agree well. For CSR we show that only dimensionless parameters, shielding parameter $\ensuremath{\Pi}$ strength ${S}_{\mathrm{csr}}$, are needed describe system. further there is strong associated with CSR, threshold, good approximation, given by...
We consider the impedance of a structure with rectangular, periodic corrugations on two opposing sides rectangular beam tube. Using method field matching, we find modes in such structure. then limit ourselves to case small corrugations, but where depth corrugation is not compared period. For generate analytical approximate solutions for wave number $k$, group velocity $v_g$, and loss factor $\kappa$ lowest (the dominant) mode which, when results complete numerical solution, agreed well....