Abstract
The evolution of thermally generated magnetic fields in a plasma undergoing a nearly spherically symmetric adiabatic compression or expansion is calculated. The analysis is applied to obtain approximate results for the development of magnetic fields in a laser‐driven compression and explosion of a pellet of nuclear fuel. Localized sources such as those occurring at composition boundaries in structured pellets or at shock fronts give stronger fields than those deriving from smoothly distributed asymmetries. Although these fields may approach 107 G in the late stages of compression, this is not expected to present difficulties for the compression process. Assuming ignition of a nuclear explosion occurs, the sources become much stronger and values of ≈1010 G are obtained at tamper boundaries assuming a 20% departure from spherical symmetry during the explosion.