Focusing moderate energy LINACs with background ion plasma

We designed, constructed, and successfully tested an Ion Focused Linear Accelerator (IFLAC) which used a background of positive ions to focus the beam and stabilize it against various instabilities. A 100 A electron beam was accelerated to approximately 120 kV over 75 cm with greater than 40% efficiency during a series of controlled experiments. The beam brightness exceeded 6 X 103 A/cm2 Sr and emittance was less than 30π mR cm. Near the end of the work a 200 A beam was accelerated through the first 3 gaps with virtually 100% efficiency. These results demonstrate the value of ion focusing in reducing the cost and complication of electron induction accelerators