STATIC ELECTRIC FOCUSING IN LOW-ENERGY LINEAR ACCELERATORS.

Static electric focusing in drift-tube linear accelerators is considered, and the possibilities of using such focusing for protons in the energy range from 50-100 keV to a few MeV are evaluated. It is shown that static focusing is only effective for relatively large velocity increments in the accelerating gaps. It is therefore necessary to increase significantly the amplitude of the accelerating field or the wavelength (to 8-24 m). The accelerator then has only a small number of gaps. The associated effect of so-called alternating self-focusing is also considered.