Energetic electrons and x-ray photons from multiterawatt Ti:sapphire lasers

The energy distribution and yield of electrons and hard x-ray photons have been investigated by irradiating tungsten and tantalum targets with ∼30 fs pulses in the intensity range between 10¹⁸-10¹⁹ W/cm² using the multiterawatt Ti:sapphire lasers from Laboratoire d'Optique Appliquee (LOA, Palaiseau, France) as well as from Physikalische-Technische Bundesanstalt (PBT, Braunschweig, Germany). For the measurement of the hard x-ray emission in the energetic range from 15 keV to 700 keV at the LOA a 9-channel spectrometer of calibrated thermoluminescence detectors (TLD) was used. The scaling of the hard x-rays was studied by varying the incident laser energy within one order of magnitude and the pulsewidth by a factor of 5. The hot electron output was investigated in the range between 300 keV-1 MeV at the new MBI Ti:sapphire laser using a time of flight spectrometer. The results indicate the sensitive interplay between the temporal laser pulse shape and laser intensity.