Abstract A new generation of field emitter array (FEA) cathode materials is under development at SAIC, in collaboration with NRL and GTE Laboratories. The emitter structures under consideration consist of large area ( ∼ 1 cm 2 ) arrays of large numbers ( ∼ 10 6 ) of microscopic field emitting tips. The structures can be fabricated so as to choose an emitter tip microstructure that is a solid cone, a hollow cylinder, or a variety of other shapes. These microstructures evidence very high local field enhancement factors, controllable from a factor of ∼ 200 to > 2000 . This large local field enhancement allows quantum field emission of significant current from the large area array while the applied macroscopic electric field is still quite low ( ∼ 20 kV/cm ). Single-tip, noninteracting particle, multigrid simulations indicate that the beam brightnesses B n = I/π 2 ϵ n 2 >10 10 A/cm 2 rad 2 may be possible. Beams with such high brightness allow for a greatly expanded field of FEL applications, including high gain and harmonic operation in the FIR wavelength regime. Experiments have so far demonstrated DC average current densities > 1 A/cm 2 , uniform emission, and improved characteristics when run for long periods of time ( > 100 h, DC ). Our present efforts are concentrated on optimizing the available cathode current density, measuring the actual beam brightness, and including self-field and 3-D effects in the numerical simulations.