The Production of Intense Nanosecond and Subnanosecond Beam Pulses from Tandem Accelerators

A short review is presented of the factors involved in the production of intense bursts of ions having nanosecond duration from tandem accelerators. For the specific example of the High Voltage Engineering Corporation´s model MP tandem it is shown that, if velocity modulation is applied to the beam at the appropriate point and if a nondispersive arrangement of elements is used in the post-acceleration beam-transport system, the existing source and the injection optics should permit pulsed beams of the hydrogen isotopes to be available at several target positions with energies up to 20 MeV, burst widths of ~ lnS and peak intensities of ~ 500¿A. The advantages are emphasized of having ions of variable energy available at the modulator and it is shown that this feature can permit the use of sources of large inherent energy spread and also the production of pulsed beams from a variety of heavy ions. The concept of multiple bunching is introduced and it is shown that the use of this technique would allow the production of burst intensities of several milliamperes and also ultra-short pulses (¿ ~ 5 × 10-11 secs).