  A review of modern high intensity H- ion sources for accelerators is
presented. The cesiation effect, a significant enhancement of negative ion
emission from gas discharges with decrease of co-extracted electron current
below negative ion current, was observed for the first time by inserting into
the discharge chamber a compound with one milligram of cesium on July 1, 1971
in the Institute of Nuclear Physics (INP), Novosibirsk, Russia. This
observation became the basis for the development of surface plasma negative ion
sources (SPS). The efficiency of negative ion generation was increased by the
invention of geometrical focusing. The magnetron-planotron with geometrical
focusing SPS is discussed. The converter SPS is reviewed. Semiplanotron SPS is
discussed. Penning discharge SPS, RF pulsed and CW SPS are reviewed. The
history of negative ion source development is reviewed. Large development
projects, including the SPS for the Large Hadron Collider (LHC) and for the
International Thermonuclear Experimental Reactor (ITER) are being conducted.
The development and fabrication of injectors with cesiated SPS has become a
billion dollars scale industry.
