The performance of a pulsed-heat-source, high-temperature inert gas MHD electrical power generator, which is a candidate space-based laser-to-electrical power converter, is examined by time-dependent, quasi-one dimensional, numerical simulation. In the present MHD generator, the inert gas is assumed to be ideally pulse heated to about 104 K within a short time (∼1 μs) in a stagnant energy input volume. The energy of the high-temperature inert gas is converted to the electricity using the medium of pure inert gas plasma without seeding. The numerical simulation results show that an enthalpy extraction ratio (= electrical output energy/pulsed heat energy) of several tens of percentage can be achieved, which is the same level as the conventional, seeded, nonequilibrium plasma MHD generator. Although there are still many phenomena to clarify and many problems to overcome to build this system, a pulsed-heat-source, high-temperature inert gas MHD generator is worth examining in more detail.