• Z.M. Dai, D.G. Li, Y. Xu, X.F. Zhao, Z. Zhao
  SINAP, Shanghai

In this paper, we study the harmonic operation of the SDUV HGHG-FEL (Phase-I), which consists of 160MeV linac, and two undulators separated by a dispersion section. A laser light at 352nm is injected into the first undulator to modulate the energy of the electron beam. This is followed by a dispersion section to produce spatial bunching at 352nm, and a second undulator which fundamental is resonant to 264nm and 3rd harmonic is resonant to 88nm. Upon passing through the second undulator, the prebunched electron beam first radiates coherently at 88nm (i.e., the 3rd harmonic of the second undulator which is integer times of the seeding laser), and then this radiation is exponentially amplified, while the fundamental of the second undulator is allowed to grow from noise. Under proper condition, the output power of the 3rd harmonic may be much higher than that of the fundamental.

• D.G. Li, Z.M. Dai, Q. Gu, Y. Xu, X.F. Zhao, Z. Zhao
  SINAP, Shanghai

In this paper, we present the numerical simulation for HGHG operation of the Shanghai deep ultra-violet free electron laser source (SDUV-FEL). In this operation, a 264nm seed laser interacts with a 277MeV, 400A, normalized emittance 4mm.rad and local energy spread 0.1% electron beam in the first wiggler(modulator) with period 5cm, total length 0.8m and parameter K=2.03, where the energy of the electron beam is modulated. Then through a dispersion section with dy/dg~6.3, the energy modulation is converted to spatial bunching. In the second wiggler (radiator) with period 2.5cm, total length 10m and parameter K=1.45, the 88nm coherent radiation is generated in the first two gain lengths and its radiation power is exponentially amplified after two gain lengths. The simulation indicates that about several hundred MW 88nm and about few MW 29.3nm radiation can be produced.

• Z. Zhao, Z.M. Dai, Q. Gu, D.G. Li
  SINAP, Shanghai

The SDUV-FEL based on a 300MeV S-band normal conducting Linac has been designed as an HGHG type high gain FEL facility. Since last December its first 100MeV Linac section has been being commissioned with a thermionic gun injector and will pass its acceptance this Autumn. After that, a photocathode injector will replace the existing the thermionic gun and bunchers of the 100MeV Linac. The photocathode gun, the magnetic bunch compressor, the FEL required beam diagnostics are under manufacture. A two-period radiator undulator prototype has been fabricated and measured, and six 1.5m radiator sections are now under manufacture. In this paper, we also briefly introduce the design optimization on the SDUV-FEL facility.