A5035411253- Particle Accelerators and Free-Electron Lasers
- Particle accelerators and beam dynamics
- Gyrotron and Vacuum Electronics Research
- Advanced X-ray Imaging Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Superconducting Materials and Applications
- Advancements in Photolithography Techniques
- Laser Design and Applications
- Particle Detector Development and Performance
- Nonlinear Dynamics and Pattern Formation
- Magnetic confinement fusion research
- Solid-state spectroscopy and crystallography
- Photocathodes and Microchannel Plates
- Astronomy and Astrophysical Research
- Laser-Plasma Interactions and Diagnostics
- Acoustic Wave Resonator Technologies
- Optical Systems and Laser Technology
- Radiation Therapy and Dosimetry
- Non-Destructive Testing Techniques
- Advanced MEMS and NEMS Technologies
- Nonlinear Optical Materials Research
- Chaos control and synchronization
- Advanced Algorithms and Applications
- Advanced Physical and Chemical Molecular Interactions
- Advanced X-ray and CT Imaging
Brookhaven National Laboratory
2005-2024
Pohang Accelerator Laboratory
2000-2019
Pohang University of Science and Technology
2000-2019
National Taiwan University
2017
China University of Geosciences (Beijing)
2015
Pohang TechnoPark (South Korea)
2006
Korea Advanced Institute of Science and Technology
1985-1988
Observation of the type-II Pomeau-Manneville intermittency was realized in a coupled nonlinear oscillator circuit employing p-n junction diode and linear elements. It seems that Hopf bifurcation period tripling are among most important precursors to intermittency. Experimental results found agree very well with numerical derived from discrete maps Pomeau-Manneville.
ATF2 is a final-focus test beam line which aims to focus the low emittance from ATF damping ring vertical size of about 37 nm and demonstrate nanometer level stability. Several advanced diagnostics feedback tools are used. In December 2008, construction installation were completed commissioning started, supported by an international team Asian, European, U.S. scientists. The present status first results described.
Abstract Onychomycosis, or fungal infection of the nail, is a disease seen frequently in clinical settings. However, rates positive identification using potassium hydroxide preparations cultures are relatively low. Precise diagnosis possible via histopathologic examination to monitor existence fungus and performance culture for confirmation. Phase‐contrast hard X‐ray microscopy synchrotron radiation provides 70‐nm spatial resolution enables imaging minute internal cellular structures. This...
Observation of ultrawide bandwidth, up to 15% full-width, high-gain operation a self-amplified spontaneous emission free-election laser (SASE FEL) is reported. This type lasing obtained with strongly chirped beam (deltaE/E approximately 1.7%) emitted from the accelerator. Because nonlinear pulse compression during transport, short, high current bunch strong mismatch errors injected into undulator, giving FEL gain. Start-to-end simulations reproduce key features measurements and provide...
The Pohang Light Source upgrade (PLS-II) project has successfully upgraded the (PLS). main goals of PLS-II are to increase beam energy 3 GeV, number insertion devices by a factor two (20 IDs), current 400 mA, and at same time reduce emittance below 10 nm using existing PLS tunnel injection system. Among 20 devices, narrow gap in-vacuum undulators in operation now more be installed later. Since these most likely produce coupled bunch instability resistive wall impedance limit stored current,...
Nonlinear dynamic characteristics of a K${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$ crystal near the ferroelectric phase transition were observed to change across temperature ${T}_{c}$. Above ${T}_{c}$ period-doubling cascades and intermittency chaos dominant signals, while locking quasiperiodicity observations below This difference was attributed in nature polarization dynamics damped-anharmonic-oscillator behavior above coupled-mode
The higher order modes (HOMs) of RF cavities at the Pohang Light Source (PLS) storage ring cause longitudinal coupled bunch mode instabilities. A feedback system (LFS) is introduced to cure these As a key component LFS, there single-ridged waveguide-overloaded cavity for bunch-by-bunch LFS kicker. Since frequency 500 MHz, bandwidth this kicker should be wider than 250 MHz damp any mode. Also, shunt impedance selected use lower power amplifier. One aluminum fabricated, and bandwidth, HOMs,...
A Brookhaven National Laboratory (BNL) GUN-IV type photocathode rf gun has been fabricated to use in femtosecond electron diffraction (FED), far infrared radiation (fs-FIR) facility, and X-ray free laser (XFEL) facilities at the Pohang Accelerator (PAL). The consists of a 1.6-cell cavity with copper cathode, solenoid magnet, beam diagnostic components auxiliary systems. We report here measurement basic parameters which confirm successful fabrication RF system. emittance evolution is measured...
Motivation: EPI-based CEST (CEST-EPI) is fast but suffers from image distortion caused by field susceptibility. Goal(s): We aimed to evaluate the effectiveness of using map generated Z-spectra achieve self-correction (DISC) for single-shot CEST-EPI without additional acquisition a map. Approach: The DISC strategy was demonstrated in experiments creatine phantom and vivo mice. CEST-RARE used as reference. Results: Without acquiring an map, retrospectively effectively corrected geometric...
Phase locking and period-doubling bifurcation are observed to characterize the nonlinear response of a driven K${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$ crystal at temperatures near ferroelectric phase transition, where may well be represented by coupled system two anharmonic oscillators, polarization-mode oscillator an elastic shear-mode piezoelectric effect.
Originally, the Pohang Light Source (PLS) storage ring was designed to store beam current up 400 mA. But owing interactions between HOMs of RF cavities and bunched beams which make coupled bunch mode instabilities (CBMIs) such as dipole, quadrupole, sextupole modes, can be stored 200 So, cure those CBMIs, a longitudinal feedback system (LFS) using parallel digital signal processors is necessary. After having considered developing cost period, it decided install LFS with electronics...
The distributed seismic data acquisition system is a critical component to telemetry digital seismograph, while the performance of seismograph subject index this system.A with high accuracy and low power dissipation which applicable large scale wired was developed accurate analog-digital conversion technology, FPGA embedded technology consumption in paper.This qualifies A class standard specified SY/T5391-2007 aspects equivalent input noise, harmonic distortion, dynamic range unique features cost.
The Pohang Light Source (PLS) storage ring uses two bunch-by-bunch feedback systems - a longitudinal system (LFS) and transverse (TFS) to cure the coupled bunch instabilities due higher order modes of RF cavities resistive wall impedance. LFS employs digital electronics developed for ALS PEPII cavity-type kicker, it was successfully commissioned in 1999 with aid SLAC. TFS analog two-tap coaxial notch filters closed orbit offset signal rejection. is now upgrade use one kicker per plane...
The beam based alignment (BBA) technique is applied to the 2-GeV storage ring of Pohang Light Source measure offsets position monitors. This measurement particularly necessary for monitors (BPMs) plugged into a long (∼10 m) aluminum chamber, since mechanical deformation vacuum chamber experienced after repeated heating outgassing process, and BPM positions are changed accordingly. A part excitation current each quadrupole magnet shunted through an electronic shunt circuit. Then, closed orbit...
In the third generation light source, photon beam position stability is critical issue on user experiment. Generally monitors have been developed for detection of real and controlled by feedback system in order to keep reference position. PLS-II, front end particular line, which monitor installed, has obtained less than rms 1μm service period. Nevertheless, detail analysis data demonstrate performance necessary, since it can be suffers from various unknown noises. (for instance, a back...