Ion sources for heavy ion fusion induction linacs

Depending on the type of beam transport selected at the front end of a heavy ion fusion driver, the optimum injector current (per beam) can vary from 0.5 to 25 A of cesium ions. The average current density should be ≥10 mA/cm 2 . So far, surface ionization sources have been used in most HIF driver designs. These sources can efficiently produce singly charged alkali ions such as Cs + and K + . Nevertheless, the gas sources and the metal vapor vacuum arc (MEVVA) sources are also potentially useful for HIF applications. Recent experimental results on ion source development are summarized.