  Recent initiatives in ultra-short, GeV electron beam generation have focused
on achieving sub-fs pulses for driving X-ray free-electron lasers (FELs) in
single-spike mode. This scheme employs very low charge beams, which may allow
existing FEL injectors to produce few-100 as pulses, with high brightness.
Towards this end, recent experiments at SLAC have produced ~2 fs rms, low
transverse emittance, 20 pC electron pulses. Here we examine use of such pulses
to excite plasma wakefields exceeding 1 TV/m. We present a focusing scheme
capable of producing ~200 nm beam sizes, where the surface Coulomb fields are
also ~TV/m. These conditions access a new regime for high field atomic physics,
allowing frontier experiments, including sub-fs plasma formation for wake
excitation.
