Time-resolvedKαspectra in high-intensity laser-target interaction

The spectrum of $K\alpha$ emission lines resulting from the interaction of a 10-μm laser at 3×${10}^{14}$ W/${\mathrm{cm}}^2$ with aluminum and titanium targets has been temporally resolved with an x-ray streak camera. With Ti targets unshifted $K\alpha$ predominates and the $K\alpha$ yield is observed to peak during the rising edge of the laser pulse. For aluminum targets the complete inner-shell transition spectrum extending up to the He-like resonance line is observed and is consistent with target heating expected from a local hot-electron flux comprising about 10% of the laser intensity during the rising slope of the pulse.