  We study the non-linear dynamics of axion inflation, capturing for the first
time the inhomogeneity and full dynamical range during strong backreaction,
till the end of inflation. Accounting for inhomogeneous effects leads to a
number of new relevant results, compared to spatially homogeneous studies: i)
the number of extra efoldings beyond slow roll inflation increases very rapidly
with the coupling, ii) oscillations of the inflaton velocity are attenuated,
iii) the tachyonic gauge field helicity spectrum is smoothed out (i.e.~the
spectral oscillatory features disappear), broadened, and shifted to smaller
scales, and iv) the non-tachyonic helicity is excited, reducing the chiral
asymmetry, now scale dependent. Our results are expected to impact strongly on
the phenomenology and observability of axion inflation, including gravitational
wave generation and primordial black hole production.
