A 90 GHz photoinjector

Photocathode RF guns depend on mode locked laser systems to produce an electron beam at a given phase of the RF. In general, the laser pulse is less than σ₂=10° of the RF phase in length and the required stability is of the order of Δφ=1°. At 90 GHz (W-band), these requirements correspond to σ_z=333 fsec and Δφ=33 fsec. A laser system with pulse lengths in the fsec regime is commercially available, the timing stability is a major concern. We propose a multi-cell W-band photoinjector that does not require a mode locked laser system, thereby eliminating the stability requirements at W-band