Magnetic Field Generation in High-Intensity-Laser–Matter Interactions

A multifluid implicit plasma simulation code has been used to study the transport of hot electrons generated by an intense $(\ge 3\times {10}^{18}\mathrm{W}/\mathrm{cm}{}^2)$ short-pulse 1.06 μm laser into plasma targets over a broad range of densities $\left[\right(0.35–200\left)n_{\mathrm{crit}}\right]$, as arising in the Fast Ignitor approach to inertial confinement fusion. The most intense (16–250 MG) magnetic fields generated in this interaction are traced to the ponderomotive push on background electrons, and tardy electron shielding. These fields can focus the heated electrons toward the axis of the beam, while impeding the direct return flow of background electrons.