Guiding femtosecond high-intensity high-contrast laser pulses by copper capillaries

Propagation of high-intensity, high-contrast ($<{10}^{-8}$), 50,fs laser pulses through triangilar copper capillaries is experimentally studied. The relative transmission through 20-mm-long, about 50,$\mu$m wide capillaries is directly measured to be 70% for input intensities up to ${10}^{17}{\text{W/cm}}^2$. The copper reflectivity in vacuum, helium, and air is measured in the intensity range of ${10}^{10}$–${10}^{17}{\text{W/cm}}^2$. No reflectivity decrease in vacuum and helium is observed, which leads to the conclusion that copper capillary waveguides can efficiently guide laser pulses of intensities up to ${10}^{19}{\text{W/cm}}^2$ on the capillary axis (that corresponds to ${10}^{17}{\text{W/cm}}^2$ on the walls). The reduction of the transmission efficiency to zero after a number of transmitted pulses is observed, which is caused by plug formation inside the capillary. The dependence of the capillary lifetime on the pulse energy is measured.