UV transient absorptions in high pressure argon excited by relativistic electrons

Influence of Ar(2)+ in an argon collisional-radiative model

A nonlinear time-dependent collisional-radiative model for recombining argon is presented. Reactions involving Ar(2)+ are taken into account and their influence is discussed. It is shown that Ar(2)+ may increase the time to reach the quasi-steady-state by a factor of 100. The calculation of the recombination rate coefficient at the quasi-steady-state is presented. An analytical expression is derived and compared with existing literature values. The importance of the increase of the quasi-steady-state time is illustrated by comparisons of excited levels population densities distribution measured in a fast moving plasma where the mechanical time scale is sufficiently short to provide a time-dependent chemistry in a reference frame moving with the flow. The high sensitivity of the results towards the electron number density is pointed out. Finally, the influence of the processes involving Ar(2)+ on the excitation temperature is discussed.

Optical-optical double resonance involving the coupling of a vacuum-ultraviolet spark source with a laser: two-step excitation in rare gases

An experimental setup including the synchronized coupling of a VUV spark source with a laser is described. Experimental results on the depletion of Ar(2), Kr(2), and Xe(2) excimer fluorescence illustrate the capability of the system.