REALIZATION OF A PERMANENT-MAGNET UNDULATOR FOR THE CLIO INFRARED FREE-ELECTRON LASER AT ORSAY

The purpose of CLIO (Collaboration pour un Laser Infra-rouge a Orsay) is to provide a tunable high-power infrared source in Orsay, at LURE. The permanent magnet undulator for the linear accelerator (linac) free electron laser is described here. This undulator consists of two independent parts of equal length and equal period, with independently adjustable magnetic gaps. Moreover, the second section can be tapered, to optimize both the gain and the energy extraction efficiency for a wide range of wavelengths. The realization of the undulator is described: mechanical system, the magnet sorting, measurements of the magnetic field for several cases of operation. The results of the modelling of the corresponding electron trajectory and spontaneous emission spectra are taken as tests of the quality of the undulator. Finally, the beam diagnostics associated with the undulator are presented: two secondary emission profile monitors and three optical transition radiation screens for electron and optical beam alignment.