Fast electron energy distribution in femtosecond laser plasma interactions

The energy distributions of fast electrons in fs laserplasma interactions have been measured using the magnetic spectrometers with various magnetic fields, fitted with the LiF thermoluminescent dosimeters (TLDs). The results show that the consistency and the important characters of energy distribution of fast electrons, which are similar to those of the experiment and simulation made by others. There is a concavity at 40 keV, which is due to the return current of cold electrons; and a local plateau of electrons with energies 100~350 keV, which is produced by several acceleration mechanisms in energy distribution. The effective temperature of fast electrons is consistent with the temperature scaling of the resonance absorption, which is due to Landau damping or wave breaking．