Vacuum and atmosphere are separated by a plasma window to facilitate nonvacuum electron-beam welding and nonvacuum material processing.

Plasma windows can separate vacuum and atmosphere, or regions of high and low vacuums, in a way which facilitates transmission of various particle beams and/or radiation from low- to high-pressure regions. In a prototype device, a stabilized plasma arc was properly configured to function as a nonsolid plasma window. Since charged particles can be focused by these arcs, focusing of such beams is a secondary function of this device.