US Patent 7605385 Electro-less discharge extreme ultraviolet light source

An electrode-less discharge source of extreme ultraviolet (EUV) radiation (10) efficiently assembles a hot, dense, uniform, axially stable plasma column (5) with magnetic pressure and inductive current drive. It employs theta-pinch-type magnetic compression of plasma confined in a magnetic mirror. Plasma, confined in a magnetic mirror, is made to radiate by resonant magnetic compression. The device comprises a radiation-source gas input nozzle (1), an optional buffer-gas input flow (2), mirror-field coils (9a, 9b), theta-pinch coils (8a, 8b), a plasma and debris dump (11), and an evacuation port (7). The circular currents yield an axially stable plasma-magnetic-field geometry, and a reproducible, stable, highly symmetrical EUV source.