  Utilizing laser plasma wakefield to accelerate ultra-high charge electron
beam is critical for many pioneering applications, for example to efficiently
produce nuclear isomers with short lifetimes which may be widely used. However,
because of the beam loading effect, electron charge in a single plasma bubble
is limited in level of hundreds picocoulomb. Here, we experimentally present
that a hundred kilo-ampere, twenty nanocoulomb, tens of MeV collimated electron
beam is produced from a chain of wakefield acceleration, via a tightly focused
intense laser pulse transversely matched in dense plasma. This ultra-intense
electron beam ascribes to a novel efficient injection that the nitrogen atom
inner shell electrons are ionized and continuously injected into multiple
plasma bubbles. This intense electron beam has been utilized to exciting
nuclear isomers with an ultra-high peak efficiency of $1.76\times10^{15}$
particles/s via photonuclear reactions. This efficient production method of
isomers can be widely used for pumping isotopes with excited state lifetimes
down to picosecond, which is benefit for deep understanding nuclear transition
mechanisms and stimulating gamma-ray lasers.
