  We investigate the main physical processes that limit the repetition rate of
capillary discharges used in laser accelerators of electrons theoretically and
with computer simulations. We consider processes in the capillary. We assume
that a cooling system independently maintains temperature balance of the
capillary, as well as a gas supply system and a vacuum system maintain
conditions outside the capillary. The most important factor, determining the
highest repetition rates in this case, is the capillary length, which governs a
refilling time of the capillary by the gas. For a short capillary, used for
acceleration of sub-GeV electron beams, the repetition rate approximately equal
to 10 kHz, which is inversely proportional to the square of the capillary
length. The effects of the capillary diameter, gas type and the gas density are
weaker.
