Conceptual Design Reports

CDR chapter 10 - Laser Systems

Laser systems will undoubtedly be crucial to determining the overall performance of FERMI. As can be seen from the previous chapters, the laser systems will include the photoinjector laser (PIL), laser heater (LH), seed laser (SL) and beam-line lasers (BLL). In addition, the timing and synchronization system  will contain a mode-locked optical master oscillator (OMO). This chapter emphasizes the PIL and SL, as the technology for the other two systems will be very similar; the OMO has already been considered in Chapter 9. The main issues related to the FERMI laser systems have been thoroughly studied during the last year, some of the important points and preliminary data have been summarized and presented in [1]. We note that nearly all the features required of the laser systems by the FERMI FEL design are within reach of readily available laser technology. In contrast, a few characteristics, such as pulse/beam shaping for the photoinjector laser as well as wavelength stability and pulse quality for the seed laser are challenging and will require additional R&D. As it will be shown later, the comparison of the existing
laser technologies for obtaining the required parameters indicated the basic unit in all cases to be a Ti:Sapphire chirped pulse amplifier pumped by diode pumped solid state lasers.
The photoinjector laser includes two amplifier stages – a regenerative stage followed by a multipass stage – to reach a pulse energy of 20 mJ in the IR. Pulse shaping is done partially in the IR, by an acoustooptic dispersive filter (DAZZLER), and is completed in UV in a transmission grating-based stretcher or Fourier-system. Beam shaping is done either in the IR or in the UV by an aspheric shaper. A small part (~400 μJ) of the IR beam is split away and transported for use by the laser heater.

Ultima modifica il Venerdì, 27 Gennaio 2023 15:50