I am currently welding joints on Aluminium EN AW 2219 without porosity, by welding cylindrical parts through a cylindrical vaccum chamber.
The vaccum chamber is made of PMMA (Plexiglas - Altuglas), thickness 2± 0.1mm, the intern presure is 5.10-3 mbar.
I am using fibre delivered CW 4kW ND:YAG...