Ultra high-gradient energy loss by a pulsed electron beam in a plasma

The plasma wake-field mechanism can be used to couple energy at a high rate from a bunched electron beam into a plasma wave. We will present results from the Fermilab A0 facility where a beam with an initial energy of 14 MeV passes through the plasma to emerge with a much broader energy spread, spanning from a low of 3 MeV to a high of over 20 MeV. Over the 8 cm length of the 10/sup 14/ cm/sup -3/ plasma, this implies a 140 MeV/m deceleration and 72 MeV/m acceleration gradient.