High intensity alkali ion sources for plasma diagnostics

The injection systems of heavy ion beam probe (HIBP) and beam emission spectroscopy plasma diagnostics must produce a beam with a high enough intensity to obtain a reliable secondary signal. In particular, it can be achieved by improvements and optimization of the ion sources. Among a variety of them, the sources with solid-state thermoionic emitters have strong advantages in simplicity and very small (0.1–1 eV) initial energy dispersion. High intensity alkali ion sources with solid-state thermoionic emitters of Li+, Na+, K+, Cs+, and Tl+ have been developed and investigated in IPP NSC “KIPT,” Kharkov, Ukraine. In a steady mode of operation the current densities up to 6 mA/cm2 are obtained with an emitter capacity up to 9 mA/h. With no significant design modifications, these ion sources are used on currently operating injectors of HIBP diagnostics on the TJ-II stellarator (Spain), tokamaks T-10, TUMAN-3M (Russia), and ISTTOK (Portugal), and the injector of the BES diagnostic on ASDEX-U tokamak (Germany).