Electromagnetic pulse generation within a petawatt laser target chamber

Abstract

Recent work has been undertaken to characterize the electromagnatic pulse (EMP) generated by the high temperature high density plasma produced by a petawatt laser. This was to evaluate the susceptibility to malfunction and damage of equipment and diagnostics for the new Orion laser. EMP measurement were made using moebius loop antennas fitted inside the target chamber of the Vulcan petawatt laser at the Rutherford Appleton Laboratory. These show the EMP as a $\text{63\hspace{0.5em}}\mathrm{MHz}$ transient which decays from a peak magnetic field of around $\text{4.3\hspace{0.5em}}\mathrm{A}/\mathrm{m}$ . A theoretical model presented assumes the EMP is produced by an impulse of ${10}^{12}$ electron emanating from the target, which charge the chamber wall causing it to ring at natural frequency. The theoretical model provides an estimate of the EMP measured in the Vulcan petawatt target chamber and will be used for the design of the Orion laser.