02 Synchrotron Light Sources and FELs

T24 Lasers

Paper Title Page
WEPD051 Ultrashort Electron Bunch Train Production by UV Laser Pulse Stacking 3210
 
  • L.X. Yan, Q. Du, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C. Liao, C.-X. Tang
    TUB, Beijing
 
 

Ultrashort relativistic electron beam can be applied to produce high power coherent THz radiation by mechanisms such as FEL, CSR, CTR et al. The THz modulated electron beams, or THz-repetition-rate ultrashort electron bunch trains exhibit further enhancement of coherent THz radiation. This article will report the experimental results on the ultrashort electron bunch train production by copper based photocathode RF gun via direct UV laser pulse stacking using birefringent α-BBO crystal serials at our laboratory. The temporal profile of the electron beam was measured by deflecting cavity. Space charge effect downstream the photocathode is simulated. This shaping method of laser pulse by α-BBO crystals can also be applied to form quasi flattop UV laser pulse for reducing the initial emittance of the electron beam from the photocathode RF gun.

 
WEPD052 Wavelength-tunable UV Laser for Electron Beam Generation with Low Intrinsic Emittance 3213
 
  • C.P. Hauri, B. Beutner, H.-H. Braun, R. Ganter, C.H. Gough, R. Ischebeck, F. Le Pimpec, M. Paraliev, M. Pedrozzi, C. Ruchert, T. Schietinger, B. Steffen, A. Trisorio, C. Vicario
    PSI, Villigen
 
 

In the framework of the SwissFEL activities at PSI we developed a powerful UV laser system delivering wavelength-tunable pulses at a central wavelength varying from 260 to 283 nm. The laser system based on a ultra-stable frequency-trippled Ti:sapphire amplifier delivers mJ pulse energy within a duration of 1-10 ps with 1.5 nm spectral width. Temporal flattop pulses are achieved by direct UV shaping with a UV Dazzler and a prism-based stretcher. The system is used to explore thermal emittance and quantum efficiency dependence on photon energy from metallic photo-cathode (Cu and Mo). With pepperpot techniques we have measured the predicted theoretical limit for thermal emittance (0.4 mm.mrad / mm rms laser spot size at 283 nm and 0.6 mm.mrad / mm at 263 nm) for metallic photocathodes.

 
WEPD054 Novel Ultrafast Mid-IR Laser System 3216
 
  • R. Tikhoplav, A.Y. Murokh
    RadiaBeam, Santa Monica
  • I. Jovanovic
    Purdue University, West Lafayette, Indiana
 
 

Of particular interest to X-ray FEL light source facilities is Enhanced Self-Amplified Spontaneous Emission (ESASE) technique. Such a technique requires an ultrafast (20-50 fs) high peak power, high repetition rate reliable laser systems working in the mid-IR range of spectrum (2μm or more). The approach of this proposed work is to design a novel Ultrafast Mid-IR Laser System based on optical parametric chirped-pulse amplification (OPCPA). OPCPA is a technique ideally suited for production of ultrashort laser pulses at the center wavelength of 2 μm. Some of the key features of OPCPA are the wavelength agility, broad spectral bandwidth and negligible thermal load.