Ultrafast laser micromachining of submillimetric de Laval nozzles in alumina for laser electron acceleration

We have explored the fabrication of submillimetric de Laval nozzles by ultrashort laser pulses micromachining in alumina, a dielectric ceramic, to generate supersonic gas jets in vacuum. The nozzles were manufactured in a home-built trepanning setup, and their geometry and surface quality dependence on the laser and machining parameters was investigated, aiming to control the jet spatial density to produce optimal gaseous targets for laser electron acceleration.