Magnetised Liner Inertial Fusion Fuel Density on the Z Machine Against the Density Ceiling

This paper computes the characteristic densities of the compressed fuel of a magnetised liner inertial fusion target from published operating parameters and compares them, quantity by quantity, with the Aldred density ceiling of 9.72e+57 kilograms per cubic metre, the neutron-branch bound at prescription coefficient one eighth. The headline comparison gives a margin of 55 orders of magnitude between the operating point and the ceiling: magnetised liner compression raises fuel density by roughly three orders of magnitude over its fill value, to a peak that remains 55 orders of magnitude below the ceiling; the scheme succeeds or fails on magnetisation, mix and stagnation symmetry, all of which act at densities the ceiling does not touch. Every number is obtained from the deposited calculation, which uses only published device parameters, internationally tabulated constants, and algebra stated in full. The result is negative in the useful sense: it shows that the ceiling imposes no constraint on the system as designed or operated, identifies the empirical and engineering limits that act instead, and states precisely what change in operating parameters would be required before the ceiling could matter. The study is a computation from stated assumptions; nothing in it is a measurement.