  We used numerical modeling to study the evolution of EUV-induced plasmas in
argon and hydrogen. The results of simulations were compared to the electron
densities measured by microwave cavity resonance spectroscopy. It was found
that the measured electron densities can be used to derive the integral amount
of plasma in the cavity. However, in some regimes, the impact of the setup
geometry, EUV spectrum, and EUV induced secondary emission should be taken into
account. The influence of these parameters on the generated plasma and the
measured electron density is discussed.
