  The pedestal profile measurements in high triangularity JET plasmas show that
with low fuelling the pedestal width decreases during the ELM cycle and with
high fuelling it stays constant. In the low fuelling case the pedestal pressure
gradient keeps increasing until the ELM crash and in the high fuelling case it
initially increases then saturates during the ELM cycle.
  Stability analysis reveals that both JET plasmas become unstable to finite-n
ideal MHD peeling-ballooning modes at the end of the ELM cycle. During the ELM
cycle, infinite-n ideal MHD ballooning modes and kinetic ballooning modes are
found to be locally stable in most of the steep pressure gradient region of the
pedestal owing to the large bootstrap current, but to be locally unstable in a
narrow region of plasma at the extreme edge.
  Unstable micro-tearing modes are found at the JET pedestal top, but they are
sub-dominant to ion temperature gradient modes. They are insensitive to
collisionality and stabilised by increasing density gradient.
