This recent work highlights the potential to induce and control annular beams of high energy electrons, which are predicted to significantly lower the energy requirements of the drive laser pulse for fast-ignition ICF.

In an article in Physical Review Letters (link opens in a new window), published today, a collaboration of researchers led by Prof Paul McKenna from the University of Strathclyde, together with the CLF’s Alex Robinson, David Neely and coworkers, have demonstrated that completely new types of fast electron transport patterns can be generated by understanding and controlling the electrical resistivity of the target material at low temperatures.

The research, investigated experimentally using the Vulcan petawatt laser (link opens in a new window)at the CLF and numerically using the STFC e-Science Facility, shows that even subtle features in the low-temperature, few-eV region of the resistivity-temperature curve can profoundly alter the fast electron transport pattern in solids.

Credit: D.A. MacLellan et al., Phys. Rev. Lett. 111, 095001 (2013)
Image: Zephyros simulation results showing high energy electron density maps in the [X-Y] mid-plane (electrons propagating left to right) and rear-surface [Y-Z] plane, demonstrating an annular fast electron beam profile. The 2D map of magnetic flux density (in Tesla) of the self-generated resistive field within the target is shown in the pane on the right.  The reversal in magnetic field direction inside the edge of the beam is induced by a gradient in target resistivity at low temperature and seeds the annular fast electron transport pattern.