Electromagnetic pulse generation in petawatt laser shots

As laser power has increased towards the petawatt region electromagnetic pulse (EMP) fields of up to 100kV/m have been recorded in the target chamber causing a real threat to the integrity of diagnostic instruments. The radiation, being in the100MHz to >1GHz frequency band also causes more widespread interference in thelaser facility. Recent work at Lawrence Livermore National Laboratory [1] points thefinger at the flux of high energy (MeV) electrons leaving the target as the primarycause of the EMP. In this report we analyse a general physical model of the modalityof the process which couples the two phenomena with the aim of devising mitigatingstrategies.