First observation of generation in the backward wave oscillator with a   "grid" diffraction grating and lasing of the volume FEL with a "grid" volume   resonator
  First observation of generation in the backward wave oscillator with a "grid" diffraction grating and lasing of the volume FEL with a "grid" volume resonator that is formed by a perodic set of metallic threads inside a rectangular waveguide is considered. 
V.G.Baryshevsky, K.G.Batrakov, N.A.Belous, A.A.Gurinovich, A.S.Lobko,   P.V.Molchanov, P.F.Sofronov, V.I.Stolyarsky