A5074250553- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Advanced X-ray Imaging Techniques
- Gyrotron and Vacuum Electronics Research
- Laser-Plasma Interactions and Diagnostics
- Photocathodes and Microchannel Plates
- Advanced Electron Microscopy Techniques and Applications
- Superconducting Materials and Applications
- Laser-Matter Interactions and Applications
- Laser Design and Applications
- Electron and X-Ray Spectroscopy Techniques
- Crystallography and Radiation Phenomena
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray and CT Imaging
- Adrenal and Paraganglionic Tumors
- Particle Detector Development and Performance
- Integrated Circuits and Semiconductor Failure Analysis
- Engineering and Test Systems
- Solid State Laser Technologies
- Gold and Silver Nanoparticles Synthesis and Applications
- Silicon and Solar Cell Technologies
- Nanowire Synthesis and Applications
- Advanced MRI Techniques and Applications
- Radio Astronomy Observations and Technology
- Plasmonic and Surface Plasmon Research
Arizona State University
2015-2024
Massachusetts Institute of Technology
2006-2015
IIT@MIT
2007
Brookhaven National Laboratory
1995-2006
National Synchrotron Light Source II
2003-2006
Bates College
2004
University of Maryland, College Park
2003
RIKEN BNL Research Center
2002-2003
Fermi National Accelerator Laboratory
1985-1995
University of Wisconsin System
1994
A high-gain harmonic-generation free-electron laser is demonstrated. Our approach uses a laser-seeded to produce amplified, longitudinally coherent, Fourier transform-limited output at harmonic of the seed laser. carbon dioxide wavelength 10.6 micrometers produced saturated, amplified second-harmonic wavelength, 5.3 micrometers. The experiment verifies theoretical foundation for technique and prepares way application this in vacuum ultraviolet region spectrum, with ultimate goal extending...
We report the first experimental results on a high-gain harmonic-generation (HGHG) free-electron laser (FEL) operating in ultraviolet. An 800 nm seed from Ti:sapphire has been used to produce saturated amplified radiation at 266 third harmonic. The confirm predictions for HGHG FEL operation: stable central wavelength, narrow bandwidth, and small pulse-energy fluctuation.
A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The based on inverse Compton scattering high brightness electron bunch picosecond laser pulse. accelerator novel high-efficiency standing-wave linac rf photoinjector powered by single ultrastable transmitter at X-band frequency. efficiency permits operation repetition rates up to 1 kHz, which further boosted 100 kHz operating trains bunches pC...
A novel method of producing intense short wavelength radiation from relativistic electrons is described. The are periodically bunched at the interest enabling in-phase superradiant emission that far more than unbunched electrons. periodic bunching achieved in steps beginning with an array beamlets emitted a nanoengineered field array. then manipulated and converted to longitudinal density modulation via transverse-to-longitudinal emittance exchange. Periodic shown be possible, partially...
Here we demonstrate the design, fabrication, and characterization of ultrafast, surface-plasmon enhanced Au nanorod optical field emitter arrays. We present a quantitative study electron emission from arrays fabricated by high-resolution electron-beam lithography excited 35 fs pulses 800 nm light. accurate models for both enhancement nanorods within high-density arrays, those nanorods. have also studied effects surface plasmon damping induced metallic interface layers at substrate/nanorod on...
We present a new method for generation of relativistic electron beams with current modulation on the nanometer scale and below. The is produced by diffracting electrons in single crystal Si, accelerating diffracted beam imaging structure, then transferring image into temporal dimension via emittance exchange. period can be tuned adjusting optics after diffraction. This tunable longitudinal have as short few angstroms, enabling production coherent hard x-rays from source based inverse Compton...
We report on an experimental investigation characterizing the output of a high-gain harmonic-generation (HGHG) free-electron laser (FEL) at saturation. A seed CO2 wavelength 10.6 microm was used to generate amplified FEL 5.3 microm. Measurement frequency spectrum, pulse duration, and correlation length verified that light is longitudinally coherent. Investigation electron energy distribution harmonic energies provides evidence for saturated HGHG operation.
Superconducting radio-frequency electron guns are viewed by many as the preferred technology for generating high-quality, high-current beams needed future high power free-electron lasers and energy recovery linacs. All previous of this type have employed elliptical cavities, but there potential advantages associated with other geometries. Here we describe design, commissioning, initial results from a superconducting gun employing quarter-wave resonator configuration, first such device to be...
We present an experimental evidence of a bunch compression scheme that uses traveling wave accelerating structure as compressor. The length issued from laser-driven radio-frequency electron source was compressed by factor $>3$ using $S$-band located immediately downstream the source. Experimental data are found to be in good agreement with particle tracking simulations.
Measurements of the thermal emittance an electron beam produced by photoemission from copper cathode a high power RF cavity are presented. The RMS normalized has been measured as function laser spot size, applied surface field, and polarization at normal incidence. Local field enhancement due to effects is found increase substantially beyond that expected for perfect planar surface.
We demonstrate the design, fabrication, characterization, and operation of high-density arrays Au nanorod electron emitters, fabricated by high-resolution beam lithography, excited ultrafast femtosecond near-infrared radiation. Electron emission characteristic multiphoton absorption has been observed at low laser fluence, as indicated power-law scaling current with applied optical power. The onset space-charge-limited strong field investigated so to determine mechanism high incident fluence....
We present recent commissioning results from the ASU Compact x-ray source (CXLS)- an inverse Compton producing sub-picosecond hard x-rays. discuss performance, flux, diagnostics, and designs for a future ICS source.
Full exploitation of emittance exchange (EEX) requires aberration-free performance a complex imaging system including active radio-frequency (rf) elements which can add temporal distortions. We investigate the an EEX line where occurs between two dimensions with normalized emittances differ by multiple orders magnitude. The transverse is exchanged into longitudinal dimension using double dogleg setup five cell rf deflector cavity. Aberration correction performed on four most dominant...
We demonstrate a fast, flexible, and accurate paraxial wave propagation model to serve as forward for propagation-based X-ray phase contrast imaging (XPCI) in parallel-beam or cone-beam geometry. This incorporates geometric effects into the multi-slice beam method. It enables rapid prototyping is well suited tomographic reconstructions. Furthermore, it capable of modeling arbitrary objects, including those that are strongly multi-scattering. Simulation studies were conducted compare our...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation W. S. Graves, E. D. Johnson, Ulc; A high resolution electron beam profile monitor its applications. AIP Conf. Proc. 10 December 1998; 451 (1): 206–213. https://doi.org/10.1063/1.57000 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search...
The DUVFEL electron linac is designed to produce sub-picosecond, high brightness bunches for driving a short wavelength FEL. Four experiments have been commissioned address the challenge of accurately measuring bunch lengths on this timescale. In frequency domain, 12 period undulator used both off-axis coherent emission and on-axis incoherent single-shot spectra. total infrared power scales inversely with length spectral cutoff an indication length. density spikes in visible spectrum may...
Saturation of a high-gain harmonic-generation free-electron laser (HGHG-FEL) at 266 nm has been accomplished the Brookhaven National Laboratory/Deep Ultra Violet Free Electron Laser Facility (BNL/DUV-FEL) by seeding with an 800 Ti:sapphire laser. We describe diagnostics used to characterize electron beam and FEL output. Analytic simulation calculations HGHG output are presented compared experimental data. also discuss chirped pulse amplification frequency seed energy beam. The third harmonic...
The nature of off-axis undulator radiation is discussed. Of particular interest coherent radiation, where the wavelengths emission are longer than electron bunch length. We show how this may be used to measure relative lengths. theory presented, and calculated spectra presented in a number cases interest.