A cylindrical gamma generator includes a coaxial RF-driven plasma ion
source and target. A hydrogen plasma is produced by RF excitation in a
cylindrical plasma ion generator using an RF antenna. A cylindrical gamma
generating target is coaxial with the ion generator, separated by plasma
and extraction electrodes which has many openings. The plasma generator
emanates ions radially over 360.degree. and the cylindrical target is
thus irradiated by ions over its entire circumference. The plasma
generator and target may be as long as desired.