The role of hot electron refluxing in laser-generated K-alpha sources

A study of the contribution of refluxing electrons in the production of K-alpha radiation from high-intensity laser irradiated thin targets has been performed. Thin copper foils both freestanding, and backed by a thick substrate were irradiated with laser pulses of energies around 100 J at intensities ranging from below 1017 to above 1019 W/cm2. At high laser intensities we find a strong reduction in the K-alpha yield from targets backed by the...