Calculating and Measuring Self-Generated Magnetic Fields in Hohlraums

The spontaneous generation of magnetic fields in laser-produced plasmas has been observed experimentally and theoretically by many authors. The main generation term for these fields is the well-known $\nabla $n$_{e}\times \nabla $T$_{e}$ term, where n$_{e}$ is the density and T$_{e}$ is the temperature. For typical laser-plasma conditions Mega-gauss magnetic fields are predicted to be generated. It has previously been shown that the main effect of these magnetic fields for Nova-scale hohlraums is to modify the electron temperature around the laser entrance hole [1]. We will review these calculations and report on recent calculations of NIF design-1 ignition hohlraums. We will also report on simulations to directly measure the magnetic fields using proton deflectometry [2]. We will assess the effect that the magnetic fields have on electron transport, laser-plasma instabilities, and symmetry in ignition and OMEGA hohlraums. [1] S. H. Glenzer, Contrib. Plasma Phys. \textbf{40}, 36 (2000). [2] A. J. Mackinnon, \textit{et al}, Rev. Sci. Instrum. \textbf{75}, 3531 (2004). This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.