  We report on the design of a new type of electron gun to be used for
experiments of infrared emission spectroscopy of rare gas excimers. It is based
on a filament heated by means of a pack of rechargeable batteries floated atop
the high-voltage power supply. The filament current is controlled by a feedback
circuit including a superluminescent diode decoupled from the high voltage by
means of an optical fiber. Our experiment requires that the charge injection is
pulsed and constant and stable in time. This electron gun can deliver several
tens of nC per pulse of electrons of energy up to $100\,$keV into the sample
cell. This new design eliminates ripples in the emission current and ensures up
to 12 hrs of stable performance.
