Diagnostics and electron-optics of a high current electron beam in the Tandem free electron laser - Status report

The electron optical design and the installation of all the Israeli Tandem FEL components, including 8 quadrupole lenses, 4 steering coils and a computerized control system, are reportedly completed. All were assembled into the high voltage terminal and controlled by a fiber optic link. Diagnostic means based on fluorescent screens and compact CCD camera cards were installed at the end of the e-gun injector. The pepper pot technique was used to study the electron beam. The experiment consists of passing the 0.5 A beam through a thin plate which is perforated with an array of 0.5 mm holes. The spots produced on a fluorescent screen placed 90 cm from the pepper pot were recorded with a CCD camera and a frame grabber. The measured normalized emittance is lower than 10πmm mrad which is quite close to the technical limit of dispenser cathode e-guns.