Pinch dynamics of the 13.5 nm EUV-emitting plasma in a LA-DPP source

Pinch dynamics of the imploding plasma and its relations with the 13.5 nm extreme ultraviolet (EUV) emissions have been experimentally investigated for a laser assisted Sn based discharge produced plasma (LA-DPP) EUV source. Plasma behaviors during the discharge are clarified using the laser aided shadowgraphic technique. Temporally and spatially resolved electron density distributions obtained by using Nomarski interferometry reveal that the maximum EUV emission corresponds to the electron density of (2.0-3.0)×10
¹⁸
cm
^-3
. The ion fraction and electron temperature of the pre-pinch plasma are estimated using a stationary collisional-radiative model.