A 10 fs X-ray emission switch driven by an intense X-ray free electron laser

We propose an intrinsic fast X-ray switch driven by the radiation emission from hollow ion states K0Ln. The switch is designed primarily for the investigation of the transient evolution of X-ray emission from high density plasmas created by short pulses (<1 ps). These plasmas usually terminate with a recombination regime at low density. If usual time integrated spectroscopic streak techniques are employed, the current time resolution is limited (>0.5 ps) and the X-ray emission from the low density regime can only be suppressed with a fast switch approach. Simulations carried out for short pulse (100 fs) intense X-ray free electron laser radiation (XFEL) interacting with dense plasmas demonstrate that the hollow ion X-ray emission switch has a time scale faster than 50 fs. This time window enables the probing of plasmas of the highest density even if time integrated spectroscopic techniques are employed.