A5010745066- Gyrotron and Vacuum Electronics Research
- Particle Accelerators and Free-Electron Lasers
- Terahertz technology and applications
- Particle accelerators and beam dynamics
- Laser-Plasma Interactions and Diagnostics
- Laser-Matter Interactions and Applications
- Advanced X-ray Imaging Techniques
- Advanced Fiber Laser Technologies
- Photonic and Optical Devices
- Crystallography and Radiation Phenomena
- Laser Design and Applications
- Solid State Laser Technologies
- Laser-induced spectroscopy and plasma
- X-ray Spectroscopy and Fluorescence Analysis
- Electron and X-Ray Spectroscopy Techniques
- Medical Imaging Techniques and Applications
- Photocathodes and Microchannel Plates
- Advanced X-ray and CT Imaging
- Photonic Crystal and Fiber Optics
- Magnetic confinement fusion research
- Spectroscopy Techniques in Biomedical and Chemical Research
- Superconducting and THz Device Technology
- Quantum optics and atomic interactions
- Pulsed Power Technology Applications
- Atomic and Molecular Physics
Tsinghua University
2015-2024
Shunde Polytechnic
2024
Key Laboratory of Nuclear Radiation and Nuclear Energy Technology
2010
Northwest Institute of Nuclear Technology
2005
University of Michigan
1998
A new technique for time-stamping bunches of electrons with terahertz pulses allows the electron arrival time to be recorded 1.5-fs accuracy, paving way greatly improved resolution in apparatuses that probe ultrafast, atomic-scale processes.
The production of ultrabright electron bunches using ionization injection triggered by two transversely colliding laser pulses inside a beam-driven plasma wake is examined via three-dimensional particle-in-cell simulations. relatively low intensity lasers are polarized along the axis and overlap with for very short time. result that residual momentum ionized electrons in transverse plane reduced, localized propagation wake. This minimizes both initial thermal emittance growth due to phase...
Tsinghua Thomson Scattering X-ray Source (TTX) is the first-of-its-kind dedicated hard source in China based on scattering between a terawatt ultrashort laser and relativistic electron beams. In this paper, we report experimental generation characterization of first pulses (51.7 keV) via head-on collision an 800 nm 46.7 MeV The measured yield 1.0 × 106 per pulse with bunch charge 200 pC energy 300 mJ. angular intensity distribution spectra are electron-multiplying charge-coupled device using...
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...
High-intensity trains of electron bunches with tunable picosecond spacing are produced and measured experimentally the goal generating terahertz (THz) radiation. By imposing an initial density modulation on a relativistic beam controlling charge over propagation, spikes several-hundred-ampere peak current in temporal profile, which several times higher than amplitudes, have been observed for first time. We also demonstrate that periodic bunch train can be varied continuously either by tuning...
We demonstrate a highly efficient method for the generation of high-field terahertz (THz) pulse train via optical rectification (OR) in congruent lithium niobate (LN) crystals driven by temporally shaped laser pulses. A narrowband THz has been successfully achieved with sub-percent level conversion efficiency and multi MV/cm peak field at 0.26 THz. For single-cycle generation, we 373- μ J energy LN crystal excited 100-mJ room temperature. The is further improved to 0.77 % pumped 20-mJ...
Advances in laser technology over the past 25 years have been impressive, particular, for Ytterbium where, nowadays, kilowatt-class systems are available. This also led to possibility provide hundreds of kilowatts power by use enhancement cavities. We report here on demonstration a stable 500 kW average high-finesse cavity. It paves way toward providing excess 1 MW and opens door breakthrough variety future applications.
Very high-average optical enhancement cavities (OECs) are being used both in fundamental and applied research. The most demanding applications require stable megawatt level average power of infrared picosecond pulses with repetition rates several tens MHz. Toward reaching this goal, we report on the achievement 710 kW a two-mirror hemispherical cavity. This result further improves state art. So far, compact high-power systems, cavity geometry optimization has been driven by need to limit...
A model of space charge influenced by multipactor electrons and plasma has been established. The positive potential/field for vacuum dielectric is analytically studied. After considering the plasma, field further shielded, saturates at higher surface accumulated field, compared with that only electrons. negative breakdown high pressure analyzed. It found potential can be nonmonotonously varied, forming a minimum well.
We propose a method based on the slice energy spread modulation to generate strong subpicosecond density bunching in high-intensity relativistic electron beams. A laser pulse with periodic intensity envelope is used modulate of beam, which can then be converted into after dispersive section. It found that double-horn distribution beam induced by very effective increase bunching. Since performed process does not suffer from space charge force or coupling between phase spaces, so it...
Generation of coherent Smith-Purcell (cSPr) and transition/diffraction radiation using a single bunch or pre-modulated relativistic electron beam is one the growing research areas aiming at development sources diagnostics for accelerators. We report results comparative experimental studies terahertz generation by an micro-bunched beams spectral properties transition SP radiation. The cSPr spectra are investigated discussed, excitations fundamental second harmonics their dependence on...
As Thomson scattering x-ray sources based on the collision of intense laser and relativistic electrons have drawn much attention in various scientific fields, there is an increasing demand for effective methods to reconstruct spectrum information ultra-short high-intensity pulses. In this paper, a precise measurement method was proposed with diffraction Highly Oriented Pyrolytic Graphite (HOPG) crystal demonstrated at Tsinghua X-ray source. The pulse diffracted by 15 mm (L) ×15 (H)× 1 (D)...
The precise timing and synchronization system is an essential part for the ultra-fast electron X-ray sources based on photocathode injector where strict among RF, laser, beams are required. In this paper, we present integrated sub-100 femtosecond developed demonstrated recently in Tsinghua University collaboration with Lawrence Berkeley National Lab. includes fiber-based CW carrier phase reference distribution delivering stabilized RF to multiple receiver clients, Low Level (LLRF) control...
High-energy electron radiography is an emerging technique for imaging matter at high energy densities ($i.e.$ under extreme temperature and pressure) with spatiotemporal resolution, but its development hindered by the technical difficulty of creating advanced optics. This study explores combination state-of-the-art high-brightness sources innovative cascaded system to make progress on problem. Interestingly, spread source seems be main obstacle further improvement resolving power this technology.
Tsinghua University is currently developing a very-high-frequency electron gun that operates in continuous-wave (cw) mode at 216.667 MHz. This will serve as the beam source for Shanghai high repetition rate XFEL and extreme light facility. The cavity profile has been optimized to minimize input power, peak surface electric field, wall power density. optimization also takes into account suppression of multipacting effect. Additionally, thermal analysis performed guide design water cooling...
The problem of a two-level atom interacting with radiation pulse is studied in the limit that atom-field detuning times duration much greater than unity. Owing to large detuning, transitions result from nonadiabatic coupling states by field. transition probability for be excited following as function field strength five different shapes: hyperbolic secant, Lorentzian, secant squared, Lorentzian and Gaussian. It shown behavior differs qualitatively these pulses. An explanation this...
Abstract Ultrashort electron bunch trains can be used for plasma wake field acceleration (PWFA) to overcome the limit of transformer ratio a single bunch, or high-power terahertz (Thz) radiation production by various mechanisms. Basic facility THz development based on ultrashort beam has been set up at accelerator lab TUB. Using birefringent crystal serials, ultraviolet (UV) pulse shaping photocathode radio frequency gun produce THz-repetition-rate train was realized. Driven such pulses,...