An inexpensive, tunable, filamentary X-ray generator, based on the bre
msstrahlung of a pulsed, high-power-density electron beam cruising alo
ng a dielectric fiber is presented. At small scale, it encodes some of
the features of an X-ray machine for triggering the energy stored in
the long-lived (HFm2)-H-178 nuclear isomer, in particular an optimum c
oupling to the active medium.