symmetry of the imploding fuel Delaying fuel heating until sufficient density is achieved Preventing premature mixing of hot and cool fuel by hydrodynamic instabilities Achieving shockwave convergence at the fuel center In order to focus the shock wave on the center of the target, the target must be made with great precision and sphericity with tolerances of no more than a few micrometres over its (inner and outer) surface. The lasers must be precisely targeted in space and time. Beam timing is relatively simple and is solved by using delay lines in the beams' optical path to achieve picosecond accuracy. The other major issue is so-called "beam-beam" imbalance and beam anisotropy. These problems are, respectively, where the energy delivered by one beam may be higher or lower than other beams impinging and of "hot spots" within a beam diameter hitting a target which induces uneven compression on the target surface, thereby forming Rayleigh-Taylor instabilities in the fuel, prematurely mixing it and reducing heating efficacy at the instant of maximum compression. The Richtmyer-Meshkov instability is also formed during the process due to shock waves. These problems have been mitigated by beam smoothing techniques and beam energy diagnostics; however, RT instability remains a major issue. Modern cryogenic hydrogen ice targets tend to freeze a thin layer of deuterium on the inside of the shell while irradiating it with a low power infrared laser to smooth its inner surface and monitoring it with a microscope equipped camera, thereby allowing the layer to be closely monitored. Cryogenic targets filled with D-T are "self-smoothing" due to the small amount of heat created by tritium decay. This is referred to as "beta-layering". In the indirect drive approach, the absorption of thermal x-rays by the target is more efficient than the direct absorption of laser light. However, the hohlraums take up considerable energy to heat, significantly reducing energy transfer efficiency. Most often, indirect drive hohlraum targets are used to simulate thermonuclear weapons tests due to the fact that the fusion fuel in weapons is also imploded mainly by X-ray radiation. ICF drivers are evolving. Lasers have scaled up from a few joules and kilowatts to megajoules and hundreds of terawatts, using mostly frequency doubled or tripled light from neodymium glass amplifiers. Heavy ion beams are particularly interesting for commercial generation, as they are easy to create, control, and focus. However, it is difficult to achieve the energy