When ultra-intense lasers interact with matter, extreme conditions are produced which cannot normally be accessed in terrestrial laboratories. These extreme states of temperature, density, and pressure form the basis for laser fusion, compact particle accelerators, and well as the exploration of the cosmos through scaled laboratory experiments of astrophysical phenomena.One feature of ultra-intense laser-solid interactions is the absorption of energy into high current relativistic electron beams. If the flow or propagation of these beams through dense matter could be controlled then many new possibilities in laser fusion and other areas of high energy density physics would emerge. Detailed control of fast electron propagation has not usually been seen as possible due to the short time-scales and small spatial scales.In previous work the PI showed that detailed control of fast electron flow might in fact be possible by using structured targets, where a guide path is defined by a more resistive material than the bulk material. Fast electron flow will then lead to resistive self-generation of magnetic field around this region which is strong enough to confine and guide the fast electrons along this path.Although promising, this concept still needs much work, and in particular physics relevant to longer (i.e. multi-ps) time-scales need to be included. In this project we will develop a numerical tool that incorporates all the relevant physics, use this to elucidate the important physics of the multi-ps regime, and then use this knowledge for Fast Ignition inertial fusion and other high energy density physics applications.