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2010-06-18 A test facility for FEL and Harmonic Generation
The test Facility at MAX-lab has been constructed and is operated in a collaboration between MAX-lab and the Helmholtz Zentrum Berlin (BESSY). The aim of the activities is to explore, test and gain experience in the field of laser seeding relevant for Free Electron Laser technology. The facility is utilising the 380 MeV linac injector, an optical klystron consisting of two undulators and a magnetic chicane and a combined gun and seeding laser system. CHG at the 6th harmonic at 43 nm (May 2010).The work on the test FEL has continued during the spring 2010. Recently Coherent Harmonic Generation in the 6 th harmonic of the seed laser (263 nm) has been recorded.
This figure shows CHG signal at both 43 and 66 nm simultaneously. The seeding was done at 263 nm and the radiator undulator wavelength was set to 133 nm. 43 nm appears as 6 th harmonic of the seed and 3rd harmonic of the radiator wavelengths. (66 nm as 4th and 2nd respectively). The background consists of mainly spontaneous undulator radiation.
CHG at 66 nm in circular polarisation (February 2010)The 4th harmonic was recorded and the polarisation switched (by phasing of the Apple II type radiator undulator) between circular and linear polarisation.
CHG at 88 nm was recorded 16 February 2010.Coherent harmonic generation at 88 nm, the 3rd harmonic of the tripled Ti:Sapphire laser seeding the system at 263 nm has been recorded. The signal-to-background levels are comparable to what was previously recorded at the 2nd harmonic.
The figure shows the coherent narrow signal on top o the spontaneous undulator radiation.
First coherent photons recorded 30 October 2009 !The first coherent photons at the fundamental (263 nm) where recorded on 30 October 2009. Using a spectrometer equipped with a N cooled CCD array the detection effiency increased and with a better discrimination of the seed-laser an enhanced signal was achieved. The laser was operated with around 25 uJ on the electron beam in a 500 fs pulse.
Figure. Intensity (au) as a function of CCD pixel (= wavelength) (pixel 535 = 262,9 nm) Blue signal: seed laser background. Green signal: Spontaneous undulator radiation without seed laser. Red signal: Undulator radiation with the seed laser.
The MAX-lab facility.
This work has been partially supported by the Swedish Research Council and by the EU Commission in the Sixth Framework Program, Contract No. 011935 – EUROFEL. |
