First lasing of the Israeli Tandem electrostatic accelerator free electron laser

First lasing at 3 mm wavelength was achieved on December 4, 1996 in our EEL employing a modified EN-Tandem electrostatic accelerator as the source of energetic free electrons. A Pierce-type electron gun capable of providing a 2A beam was installed at the entrance to the accelerator and operated at 1.4A level, while the wiggler (λ_w = 4.4cm, N_w = 26) was located in the center of the accelerator, inside the positive HV terminal. The electron gun voltage was V_gun = 43 kV and the terminal operating voltage V_term = 1.4 MV. The resonator, consisting of two parallel curved plates waveguide terminated by wave splitters at its both ends, was mounted inside the wiggler. Radiation pulses at 100.5 GHz of 2 μsec duration and 1200 W of power were obtained at intervals of 15 sec.