IONIZATION AND PULSE LETHARGY EFFECTS IN INVERSE CHERENKOV ACCELERATORS

Ionization processes and pulse lethargy limit the pulse duration, acce lerating gradient, and maximum energy gain in the inverse Cherenkov ac celerator (ICA). These limits are obtained for two ICA waveguide confi gurations: (i) lined with a dielectric or (ii) filled with a neutral g as. Ionization of the dielectric or gas, by the electromagnetic driver , can modify the dispersive properties, altering the accelerating fiel d phase velocity, causing particle slippage, and disrupting the accele ration. In addition, the electrons can outrun the pulse (pulse letharg y), terminating the acceleration. Limitations due to ionization and pu lse lethargy on the accelerating gradient, pulse duration, and maximum energy gain are obtained and illustrated by several examples. (C) 199 7 American Institute of Physics.